Nafion / Au / TiO2-PCNF / CILE composite modified electrode and preparation method and application thereof

Abstract

The invention provides a Nafion / Au / TiO2-PCNF / CILE composite modified electrode as well as a preparation method and application thereof, and belongs to the technical field of electrochemical sensors. According to the preparation method, a carbon ion liquid electrode is sequentially coated with titanium dioxide coated porous carbon nanofibers, Au nanoparticles are electrically deposited, and a Nafion film is coated, namely, the Nafion / Au / TiO2-PCNF / CILE composite modified electrode is prepared by adopting a layered dispensing method. In a PBS buffer solution with the pH value of 3.0, the Nafion / Au / TiO2-PCNF / CILE composite modified electrode has a good electrocatalytic oxidation effect on rutin, the linear range is 0.0001-20 [mu] mol / L, the detection limit is 0.045 nmol / L, the linear range is wide, the detection limit is low, the sensitivity is high, and the Nafion / Au / TiO2-PCNF / CILE composite modified electrode can be well applied to detection of the content of rutin in a target object.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical sensors, and in particular to a Nafion / Au / TiO 2 -PCN F / CILE composite modified electrode and its preparation method and application. Background Art

[0002] Rutin is derived from traditional Chinese medicine. As a vitamin P, it belongs to the glycoside class of dehydroflavonoids. It usually coexists with vitamin C in food. The synergistic effect between rutin and vitamin C affects thyroid activity, maintains and restores vascular elasticity, reduces capillary permeability, promotes cell proliferation, and has anti-inflammatory effects. In addition, rutin also performs well in the treatment of diseases such as hypertension, diabetes, retinal hemorrhage and cerebral hemorrhage, and has antiviral function. As a natural sunscreen ingredient, rutin can also effectively absorb X-rays and ultraviolet rays. However, rutin also has certain side effects and needs to be used under the guidance of a doctor to avoid potential risks caused by overdose. If depressive symptoms occur during the use of rutin, the drug should be stopped or reduced immediately to prevent the condition from worsening and increase the difficulty of treatment. In addition, children and pregnant women should be particularly cautious when using rutin. Therefore, it is crucial to perform high-sensitivity detection of rutin.

[0003] However, since the content of rutin in the human body is extremely low, it is particularly important to achieve rapid and highly sensitive detection of rutin. Summary of the invention

[0004] The object of the present invention is to provide a Nafion / Au / TiO 2 -PCNF / CILE composite modified electrode and its preparation method and application can detect rutin quickly and with high sensitivity.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a Nafion / Au / TiO 2 -The preparation method of PCNF / CILE composite modified electrode comprises the following steps:

[0007] The solution of titanium dioxide coated porous carbon nanofibers was coated on the carbon ion liquid electrode to obtain TiO 2 -PCNF / CILE electrodes;

[0008] The TiO 2 -PCNF / CILE electrode was electro-deposited in gold salt solution to obtain Au / TiO 2 -PCNF / CILE electrodes;

[0009] The Nafion ethanol solution was coated on the Au / TiO2 -PCNF / CILE electrode to obtain Nafi on / Au / TiO 2 -PCNF / CILE composite modified electrode.

[0010] Preferably, the titanium dioxide coated porous carbon nanofibers are 2 -The coating amount on the PCNF / CILE electrode is 0.01~0.1mg / cm 2 .

[0011] Preferably, the gold salt solution comprises HAuCl 4 The solution has a concentration of 1.0 to 3.0 mmol / L.

[0012] Preferably, the deposition potential of the electrodeposition is -0.2 to -0.5 V, and the deposition time is 50 to 200 s.

[0013] Preferably, the Au / TiO 2 -The deposition amount of Au on PCNF / CILE electrode is 1.0~5.0μg / cm 2 .

[0014] Preferably, the volume concentration of the Nafion ethanol solution is 3.0-7.0%.

[0015] Preferably, the Nafion / Au / TiO 2 -The coating amount of Nafion on the PCNF / CILE composite modified electrode is 0.5~2.0mg / cm 2 .

[0016] The present invention provides Nafion / Au / TiO prepared by the above preparation method 2 -PCNF / CILE composite modified electrode.

[0017] The present invention also provides the Nafion / Au / TiO 2 -Application of PCNF / CILE composite modified electrode in detection of rutin.

[0018] Preferably, the application method comprises the following steps:

[0019] Nafion / Au / TiO 2 -PCNF / CILE composite modified electrode was used as the working electrode. In a three-electrode system, PBS buffer solution with pH = 3.0 was used as the electrolyte solution to carry out electrochemical reaction on the rutin-containing sample and calculate the rutin content.

[0020] Beneficial effects of the present invention:

[0021] The present invention provides a Nafion / Au / TiO 2 -PCNF / CILE composite modified electrode, firstly, a solution of titanium dioxide coated porous carbon nanofibers was coated on the carbon ion liquid electrode, and then the obtained TiO 2 -PCNF / CILE electrode was electroplated in a gold salt solution, and then Nafion ethanol solution was coated on the resulting Au / TiO 2 -PCNF / CILE electrode, that is, Nafion / Au / TiO 2 -PCNF / CILE composite modified electrode; the titanium dioxide coated porous carbon nanofibers have good conductivity and abundant specific surface area, which can effectively promote the electron transfer of rutin on the modified electrode surface; the electrode modified with precious metal nanoparticles, especially Au nanoparticles, shows high electrocatalytic activity for compounds with slow redox process on the bare electrode; in addition, the synergistic effect between titanium dioxide coated porous carbon nanofibers and Au nanoparticles can greatly enhance the catalytic activity of the electrode surface modification material.

[0022] In a PBS buffer solution with a pH of 3.0, the Nafion / Au / TiO 2 -PCNF / CI LE composite modified electrode has a good electrocatalytic oxidation effect on rutin, with a linear range of 0.0001-20μmol / L and a detection limit of 0.045nmol / L. It has a wide linear range, a low detection limit and high sensitivity, and can be well used to detect the content of rutin in the target object. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The Au / TiO obtained in Example 2 2 -Schematic diagram of the modification process of PCNF / CILE composite modified electrode;

[0024] Figure 2 This is a scanning electron microscope (SEM) image of the titanium dioxide-coated porous carbon nanofiber composite material obtained in Example 1;

[0025] Figure 3 Cyclic voltammetry curves of the electrodes obtained in Example 2 and Comparative Examples 1-2 in a 0.1 mmol / L rutin PBS buffer solution, wherein curve a is the cyclic voltammetry curve of Comparative Example 1, curve b is the cyclic voltammetry curve of Comparative Example 2, and curve c is the cyclic voltammetry curve of Example 2;

[0026] Figure 4 A is the cyclic voltammetry curve of the electrode obtained in Example 1 in rutin PBS buffer solutions with different pH values, wherein curves a to d are cyclic voltammetry curves of pH = 2.5, 3, 3.5 and 4.0, respectively; Figure 4B is the relationship between the cyclic voltammetry oxidation peak current and pH value;

[0027] Figure 5 A in the figure is the cyclic voltammetry curve of the electrode with different modification amount of titanium dioxide coated porous carbon nanofiber material in 0.1mmol / L rutin PBS buffer solution, wherein curves b to e represent the cyclic voltammetry curves of comparative examples 2, 3, 4 and 5 respectively; Figure 5 B in the figure is the relationship between the cyclic voltammetry oxidation peak current and the modification amount of the titanium dioxide coated porous carbon nanofiber material;

[0028] Figure 6 A is the cyclic voltammetry curve of the electrode obtained in Example 1 in rutin PBS buffer solution at different scan rates, wherein curves a to j represent the cyclic voltammetry curves at scan rates of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 V / s, respectively; Figure 6 Where B is the square root of the redox peak current (Ipa, Ipc) and the scan rate υ 0.5 ) between the linear relationship curve; Figure 6 C in the figure is the linear relationship curve between the redox peak potential (Epa, Epc) and the logarithm of the scan rate (lnυ);

[0029] Figure 7 The differential pulse voltammetry (DP V) curves of the electrode obtained in Example 1 for rutin solutions of different concentrations are shown in FIG. Figure 7 A is a DPV curve diagram when the concentration of rutin is in the range of 0.0001 to 0.01 μmol / L, wherein curves a to k represent DPV curve diagrams when the concentration of rutin is in the range of 0.0001 μmol / L, 0.0002 μmol / L, 0.0004 μmol / L, 0.0006 μmol / L, 0.0008 μmol / L, 0.001 μmol / L, 0.002 μmol / L, 0.004 μmo l / L, 0.006 μmol / L, 0.008 μmol / L, and 0.01 μmol / L, respectively; Figure 7 The DPV curve of rutin concentration in B is in the range of 0.01 to 20 μmol / L, wherein curves a to o represent the DPV curves when the rutin range is 0.01 μmol / L, 0.05 μmol / L, 0.1 μmol / L, 0.3 μmol / L, 0.5 μmol / L, 0.8 μmol / L, 1 μmol / L, 2 μmol / L, 4 μmol / L, 8 μmol / L, 10 μmol / L, 12 μmol / L, 14 μmol / L, 18 μmol / L, and 20 μmol / L, respectively; Figure 7 In the range of rutin concentration from 0.0001 to 0.01 μmol / L, the oxidation peak current of C showed a linear relationship with the rutin concentration; Figure 7 In the rutin concentration range of 0.01~20μmol / L, there is a linear relationship between the oxidation peak current and the rutin concentration. DETAILED DESCRIPTION

[0030] The present invention provides a TiO 2 -The preparation method of PCNF / Au composite modified electrode comprises the following steps:

[0031] The solution of titanium dioxide coated porous carbon nanofibers was coated on the carbon ion liquid electrode to obtain TiO 2 -PCNF / CILE electrodes;

[0032] The TiO 2 -PCNF / CILE electrode was electro-deposited in gold salt solution to obtain Au / TiO 2 -PCNF / CILE electrodes;

[0033] The Nafion ethanol solution was coated on the Au / TiO 2 -PCNF / CILE electrode to obtain Nafi on / Au / TiO 2 -PCNF / CILE composite modified electrode.

[0034] In the present invention, unless otherwise specified, the required raw materials for preparation are all commercially available products well known to those skilled in the art.

[0035] The present invention preferably polishes the carbon ion liquid electrode on polishing paper to a mirror surface, coats a solution of titanium dioxide-coated porous carbon nanofibers on the carbon ion liquid electrode, and dries in the dark at room temperature to obtain TiO 2 -PCNF / CILE electrodes.

[0036] In the present invention, the preparation process of the carbon ion liquid electrode preferably includes: mixing graphite powder, ionic liquid and liquid paraffin, grinding in a mortar, filling the obtained carbon paste into a glass electrode tube and compacting it, inserting a copper wire as a conductor, and obtaining a carbon ion liquid electrode (denoted as CILE); the mass ratio of the graphite powder to the ionic liquid is preferably (1.5-2.5):1, and more preferably (1.5-2.0):1; the mass volume ratio of the ionic liquid to the liquid paraffin is preferably 1g:500-700μL, and more preferably 1g:500-600μL; the ionic liquid is preferably N-hexylpyridinium hexafluorophosphate (HPPF 6 ); the grinding time is preferably ≥2.5h, more preferably 2.5h; the inner diameter of the glass electrode tube is preferably 6mm.

[0037] In the present invention, the porous structure on the surface of the porous carbon fiber is preferably used as the growth point, the titanium dioxide nanosheet is used as the growth phase, and the titanium dioxide-coated porous carbon nanofiber composite material is prepared by a secondary nucleation method. The preparation process of the titanium dioxide-coated porous carbon nanofiber is preferably referred to "Lu Yaoyao, Ye Juntao, Ruan Chengxiang, et al. Preparation of titanium dioxide / porous carbon nanofiber composite materials and their photocatalytic properties. Journal of Textile Research, 2024, 45(04): 67-75. DOI: 10.13475 / j.fzxb.2023040 3001”, the specific preparation process preferably includes: slowly dropping 5 mL of tetra-n-butyl titanate into 20 mL of anhydrous ethanol, stirring magnetically for 30 minutes, adding 1 mL of hydrogen fluoride, and continuing stirring for 30 minutes; transferring the obtained mixed solution to a high-pressure reactor containing porous carbon nanofiber material, reacting at 180°C for 12 hours; after cooling, washing the product with distilled water and anhydrous ethanol for several times until the pH value is neutral, and drying it in a 60°C oven for 8 hours to obtain a titanium dioxide-coated porous carbon nanofiber composite material (referred to as TiO 2 -PCNF); Titanium dioxide coated porous carbon nanofibers have good conductivity and large specific surface area (628.8m 2 / g), which can effectively promote the electron transfer of rutin on the modified electrode surface.

[0038] In the present invention, the titanium dioxide coated porous carbon nanofiber solution is obtained by dissolving the titanium dioxide coated porous carbon nanofiber material in ethanol, and is denoted as TiO 2 -PCNF solution, the TiO 2 The solid content of the -PCNF solution is preferably 0.228 wt%.

[0039] In the present invention, the titanium dioxide coated porous carbon nanofibers are 2 - The coating amount on the PCNF / CILE electrode is preferably 0.01 to 0.1 mg / cm 2 , more preferably 0.0397 to 0.0567 mg / cm 2 , more preferably 0.0511 to 0.0567 mg / cm 2 .

[0040] The present invention preferably comprises TiO 2 -PCNF / CILE electrode was placed in a gold salt solution for electrodeposition, then taken out, washed and dried naturally to obtain Au / TiO 2 -PCNF / CILE electrode; the deposition of Au nanoparticles is beneficial to increase the catalytic activity of the electrode. 2 - PCNF / CILE electrode deposition of Au can achieve TiO 2-PCNF is fixed and encapsulated on the electrode surface, thereby improving the stability and electrochemical performance of the electrode.

[0041] In the present invention, the gold salt solution preferably includes HAuCl 4 The mass concentration of the gold salt solution is preferably 1.0 to 3.0 mmol / L, and more preferably 2.0 mmol / L.

[0042] In the present invention, the deposition potential of the electrodeposition is preferably -0.2 to -0.5 V, more preferably -0.3 to -0.5 V, and the deposition time is preferably 50 to 200 s, more preferably 100 to 200 s.

[0043] In the present invention, the Au / TiO 2 The deposition amount of Au on the PCNF / CILE electrode is preferably 1.0 to 5.0 μg / cm 2 , more preferably 1.21 to 4.86 μg / cm 2 , more preferably 2.42 to 4.86 μg / cm 2 .

[0044] The present invention preferably coats the Au / TiO 2 -PCNF / CILE electrode to obtain Nafion / Au / TiO 2 -PCNF / CILE composite modified electrode.

[0045] In the present invention, the volume concentration of the Nafion ethanol solution is preferably 3.0-7.0%, more preferably 5.0-7.0%; the volume of the Nafion ethanol solution is preferably 4-10 μL, more preferably 8-10 μL.

[0046] In the present invention, the Nafion / Au / TiO 2 The coating amount of Nafion on the PCNF / CILE composite modified electrode is preferably 0.5-2.0 mg / cm 2 , more preferably 0.851 to 1.98 mg / cm 2 g, more preferably 1.418 mg / cm 2 .

[0047] The present invention provides Nafion / Au / TiO prepared by the above preparation method 2 -PCNF / CILE composite modified electrode.

[0048] The present invention also provides the Nafion / Au / TiO 2-Application of PCNF / CILE composite modified electrode in detection of rutin.

[0049] In the present invention, the method of application preferably comprises the following steps:

[0050] TiO 2 -PCNF / Au composite modified electrode is used as working electrode, platinum electrode is used as auxiliary electrode, and saturated calomel electrode is used as reference electrode to form a three-electrode system;

[0051] Using PBS buffer solution with pH=3.0 as the electrolyte solution, 50 mL of the buffer solution was taken into a beaker, and different volumes of rutin standard solution were added thereto, and sample solutions with different contents were obtained by dilution. The sample solutions were tested by differential pulse voltammetry (DPV).

[0052] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0053] Example 1

[0054] 1.5g graphite powder, 1g HPPF 6 Mix with 500 μL liquid paraffin and grind in a mortar for 2.5 h to obtain a carbon paste, which is then filled into a glass electrode tube with an inner diameter of 6 mm and compacted, and a copper wire is inserted as a conductor to obtain a carbon ion liquid electrode, denoted as CILE;

[0055] 5 mL of tetrabutyl titanate was slowly added dropwise to 20 mL of anhydrous ethanol, and after magnetic stirring for 30 min, 1 mL of hydrogen fluoride was added and stirred for 30 min. The resulting mixed solution was transferred to a high-pressure reactor containing porous carbon nanofiber material and reacted at 180 ° C for 12 h. After cooling, the product was washed with distilled water and anhydrous ethanol several times until the pH value was neutral, and dried in an oven at 60 ° C for 8 h to obtain a titanium dioxide-coated porous carbon nanofiber composite material, which was recorded as TiO 2 -PCNF;

[0056] The CILE surface was polished to a mirror finish on polishing paper, and 8 μL of 1.8 mg / mL TiO 2 -PCNF solution (solvent is ethanol) was drop-coated on the surface of carbon ion liquid electrode and dried naturally under room temperature and away from light to obtain TiO 2 -PCNF / CILE electrode, titanium dioxide coated porous carbon nanofibers on TiO 2 -PCNF / CI coating amount on LE electrode is 0.0511mg / cm 2 ;

[0057] TiO 2-PCNF / CILE electrode was placed in HAuCl with a concentration of 2.0 mmol / L 4 Electrodeposition was carried out in the solution with a deposition potential of -0.3 V and a deposition time of 100 s. The Au / TiO 2 -PCNF / CILE electrode, Au / TiO 2 -The deposition amount of Au on the PCNF / CILE electrode is 2.42 μg / cm 2 ;

[0058] 8 μL of 0.5% Nafion ethanol solution was drop-coated on the Au / TiO 2 -PCNF / CILE electrode surface, dried in dark at room temperature, and stored in the dark to obtain Nafion / Au / TiO 2 -PCNF / CILE composite modified electrode, Nafion / Au / TiO 2 -The coating amount of Nafion on the PCNF / CILE composite modified electrode is 1.418 mg / cm 2 .

[0059] Example 2

[0060] The only difference from Example 1 is:

[0061] Get Au / TiO 2 -PCNF / CILE electrode is the electrode obtained in Example 2 (the electrode modification process is as follows Figure 1 ), without coating with Nafion ethanol solution.

[0062] Comparative Example 1

[0063] 1.5g graphite powder, 1g ionic liquid HPPF 6 Mix with 500 μL of liquid paraffin and grind in a mortar for 2.5 h to obtain a carbon paste. Fill the carbon paste into a glass electrode tube with an inner diameter of 6 mm and compact it. Insert a copper wire as a conductor to obtain a carbon ion liquid electrode CILE, which is stored in a dark place.

[0064] Comparative Example 2

[0065] 1.5g graphite powder, 1g ionic liquid HPPF 6 Mix with 500 μL of liquid paraffin and grind in a mortar for 2.5 h to obtain a carbon paste. Fill the carbon paste into a glass electrode tube with an inner diameter of 6 mm and compact it. Insert a copper wire as a conductor to obtain a carbon ion liquid electrode CILE.

[0066] The surface of the carbon ion liquid electrode was polished to a mirror finish on polishing paper, and 8 μL of 1.8 mg / mL TiO 2-PCNF solution was drop-coated on the CILE surface and dried naturally at room temperature in the dark to obtain TiO 2 -PC NF / CILE electrode, TiO on the electrode 2 -PCNF loading per unit area is 0.0511 mg / cm 2 , store in a dark place.

[0067] Comparative Example 3

[0068] 1.5g graphite powder, 1g ionic liquid HPPF 6 Mix with 500 μL of liquid paraffin and grind in a mortar for 2.5 h to obtain a carbon paste. Fill the carbon paste into a glass electrode tube with an inner diameter of 6 mm and compact it. Insert a copper wire as a conductor to obtain a carbon ion liquid electrode.

[0069] The surface of the carbon ion liquid electrode was polished to a mirror finish on polishing paper, and 8 μL of 1.4 mg / mL TiO 2 -PCNF solution was drop-coated on the surface of carbon ion liquid electrode and dried naturally under room temperature and away from light to obtain TiO 2 -PCNF / CILE electrode, TiO on the electrode 2 -PCNF loading per unit area is 0.0397 mg / cm 2 , store in a dark place.

[0070] Comparative Example 4

[0071] 1.5g graphite powder, 1g ionic liquid HPPF 6 Mix with 500 μL of liquid paraffin and grind in a mortar for 2.5 h to obtain a carbon paste. Fill the carbon paste into a glass electrode tube with an inner diameter of 6 mm and compact it. Insert a copper wire as a conductor to obtain a carbon ion liquid electrode.

[0072] The surface of the carbon ion liquid electrode was polished to a mirror finish on polishing paper, and 8 μL of 1.6 mg / mL TiO 2 -PCNF solution was drop-coated on the CILE surface and dried naturally at room temperature in the dark to obtain TiO 2 -PC NF / CILE electrode, TiO on the electrode 2 -PCNF loading per unit area is 0.0454 mg / cm 2 , store in a dark place.

[0073] Comparative Example 5

[0074] 1.5g graphite powder, 1g ionic liquid HPPF 6Mix with 500 μL of liquid paraffin and grind in a mortar for 2.5 h to obtain a carbon paste. Fill the carbon paste into a glass electrode tube with an inner diameter of 6 mm and compact it. Insert a copper wire as a conductor to obtain a carbon ion liquid electrode.

[0075] The surface of the carbon ion liquid electrode was polished to a mirror finish on polishing paper, and 8 μL of 2.0 mg / mL TiO 2 -PCNF solution was drop-coated on the CILE surface and dried naturally at room temperature in the dark to obtain TiO 2 -PC NF / CILE electrode, TiO on the electrode 2 -PCNF loading per unit area is 0.0567 mg / cm 2 , store in a dark place.

[0076] Characterization and performance testing

[0077] 1. The titanium dioxide-coated porous carbon nanofiber composite material in Example 1 was observed using a scanning electron microscope (SEM). Figure 2 .

[0078] like Figure 2 As shown in the figure, the titanium dioxide-coated porous carbon nanofiber composite material prepared in Example 1 has a fiber network structure, and the sheet-like TiO 2 The uniform loading on the PCNF surface indicates that it provides a high specific surface area and has abundant active sites, which significantly improves the material adsorption and electron transfer capabilities of the electrode surface.

[0079] 2. At 10mmol / LK 3 [Fe(CN) 6 ] and 0.5 mol / L KCl mixed electrolyte, the electrodes prepared in Examples 1-2 and Comparative Examples 1-2 were used as working electrodes, platinum electrodes were used as auxiliary electrodes, and saturated calomel electrodes were used as reference electrodes to form a three-electrode system. AC impedance tests were conducted in the above three-electrode system, with a scanning frequency range of 0.01 to 10 6 Hz, the results are shown in Table 1.

[0080] Table 1 Electrochemical AC impedance values ​​of the electrodes obtained in Examples 1 to 2 and Comparative Examples 1 to 2

[0081] Test example Impedance(Ω) Example 1 37.39 Example 2 31.96 Comparative Example 1 47.49 Comparative Example 2 36.19

[0082] As can be seen from Table 1, the impedance values ​​of Examples 1 to 2 and Comparative Example 2 are significantly lower than those of Comparative Example 1, indicating that the introduction of titanium dioxide-coated porous carbon nanofibers can effectively reduce the electron transfer resistance; the impedance value of Example 2 is lower than that of Comparative Example 2, indicating that the introduction of Au nanoparticles can also reduce the electron transfer resistance; the impedance value of Example 1 is higher than that of Example 2, indicating that the non-conductive Nafion membrane hinders the transfer of electrons, but considering comprehensively that the Nafion membrane can prevent the leakage and shedding of the electrode modification material and prolong the service life of the electrode, it is used to modify the electrode in Example 1.

[0083] 3. Study on the electrochemical behavior of rutin on electrodes:

[0084] Dissolve 0.03 g of rutin in 5 mL of ethanol to obtain rutin mother solution;

[0085] Using a PBS buffer solution with a pH of 3.0 as an electrolyte solution, adding rutin stock solution thereto, and diluting to obtain a rutin solution with a concentration of 0.1 mmol / L;

[0086] The electrodes obtained in Example 2 and Comparative Examples 1-2 were used to perform CV scanning on a 0.1 mmol / L rutin solution at a scanning speed of 100 mV / s. The scanning results are shown in Figure 3 ; wherein curve a is the cyclic voltammetry curve of comparative example 1, curve b is the cyclic voltammetry curve of comparative example 2, and curve c is the cyclic voltammetry curve of embodiment 2.

[0087] Depend on Figure 3 It can be seen that in Comparative Example 1 (curve a), a pair of obvious redox peaks appeared in the rutin solution, and the peak current was 8.79 μA;

[0088] The oxidation peak current of Comparative Example 2 (curve b) in rutin solution is 55.17 μA, which is 6.27 times that of Comparative Example 1. This is mainly due to the fact that TiO 2 -PCNF has a large specific surface area, which can effectively enrich rutin on the electrode surface and accelerate the electron transfer rate on the electrode surface, thereby improving the sensitivity of the sensor;

[0089] The oxidation peak current generated in Example 2 (curve c) in the rutin solution is 97.98 μA, which is nearly doubled compared with Comparative Example 2. This is mainly due to the good conductivity and catalytic activity of Au nanoparticles.

[0090] 4. Optimize the pH value of PBS electrolyte solution in the test conditions:

[0091] The electrode obtained in Example 1 was used to perform CV scanning on 0.1 mmol / L rutin solution in PBS buffer solutions with different pH values. The scanning speed was 100 mV / s. The scanning results are shown in Figure 4; Figure 4 Curves a to d in A are cyclic voltammetry curves at pH = 2.5, 3, 3.5 and 4.0 respectively; Figure 4 B is the relationship between the cyclic voltammetry oxidation peak current and pH.

[0092] Depend on Figure 4 As shown in Figure B, the pH value of the buffer solution has a great influence on the electrochemical reaction of rutin molecules: when pH = 3, the current is the largest, because the electrochemical reaction of rutin molecules requires the participation of protons. When the pH is low, the concentration of hydrogen ions is high, which is conducive to the occurrence of electrochemical reactions. Therefore, PBS with a pH of 3 is selected as the electrolyte solution.

[0093] 5. TiO 2 -The effect of the concentration of PCNF dispersion on the detection performance of the modified electrode:

[0094] Using PBS buffer solution with pH=3 as electrolyte solution, the electrodes obtained in Comparative Examples 2 to 5 were used to perform CV scanning on 0.1mmol / L rutin PBS buffer solution at a scanning speed of 100mV / s. The scanning results are shown in Figure 5 A, wherein curves b to e represent the cyclic voltammetry curves produced after scanning of the electrodes obtained in Comparative Examples 2, 3, 4 and 5, respectively; Figure 5 B in the figure is the relationship between the cyclic voltammetry oxidation peak current and the modification amount of the titanium dioxide coated porous carbon nanofiber material.

[0095] Depend on Figure 5 From B, we can see that TiO 2 The concentration of the PCNF dispersion added has a great influence on the electrochemical reaction of rutin. 2 When the concentration of the PCNF dispersion increased from 1.4 mg / mL to 1.8 mg / mL, the peak current gradually increased. When the dispersion concentration continued to increase to 2.0 mg / mL, the peak current decreased. When the dispersion concentration was 1.8 mg / mL, the peak current was the largest. Therefore, 1.8 mg / mL was selected as the concentration of TiO 2 - Concentration of PCNF dispersion.

[0096] 6. Effect of scan rate on the electrochemistry of rutin

[0097] In order to study the effect of scan rate on the redox process of the electrode obtained in Example 1 in a 0.1 mmol / L rutin solution, a PBS buffer solution with pH = 3 was used as the electrolyte solution. The electrode obtained in Example 1 was used to perform CV scans on a 0.1 mmol / L rutin PBS buffer solution at different scan rates. The scan results are shown in FIG. Figure 6 , Figure 6A is the cyclic voltammetry curve of Example 1 in 0.1 mmol / L rutin PBS buffer solution at different scan rates, and the scan rates from a to j are 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 V / s, respectively; Figure 6 The redox peak current (Ipa, Ipc) of B is related to the square root of the scan rate υ (v 0.5 ) between the linear relationship curve; Figure 6 Linear relationship curve between C redox peak potential (Epa, Epc) and logarithm of scan rate (lnv);

[0098] Depend on Figure 6 As shown in Figure A, with the increase of scan rate, the redox peak current and redox peak potential (Ep) also increase, indicating a quasi-reversible electrochemical reaction;

[0099] Depend on Figure 6 As shown in Figure B, the linear relationship between the redox peak current (Ipa, Ipc) and the square root of the scan rate v is shown in Figure 2. The linear regression equations are Ipc (μA) = 77.67 + 474.41v 0.5 and Ipa(μA)=-140.10-404.28υ 0.5 , indicating that rutin is diffusion-controlled on the sensor surface;

[0100] Figure 6 Where C is the relationship between Ep and lnv. According to Laviron theory, we can calculate the electron transfer coefficient (α) = 0.45, the number of reaction transfer electrons (n) = 2.84, and the electrode reaction rate constant (Ks) = 4.97s -1 .

[0101] 7. Nafion / Au / TiO 2 -Electrocatalysis of rutin by PCNF / CILE:

[0102] The catalytic effect of the electrode obtained in Example 1 on rutin was investigated by differential pulse voltammetry (DPV). A PBS buffer solution with pH = 3 was used, and rutin solutions of different concentrations were added thereto. After uniform stirring, DPV tests were performed. The differential pulse voltammetry curves (DPV) of rutin solutions of different concentrations were shown in FIG. Figure 7 ;in Figure 7A is a DPV curve diagram when the concentration of rutin is in the range of 0.0001 to 0.01 μmol / L, wherein curves a to k represent DPV curve diagrams when the concentration of rutin is in the range of 0.0001 μmol / L, 0.0002 μmol / L, 0.0004 μmol / L, 0.0006 μmol / L, 0.0008 μmol / L, 0.001 μmol / L, 0.002 μmol / L, 0.004 μmol / L, 0.006 μmol / L, 0.008 μmol / L, and 0.01 μmol / L, respectively; Figure 7 B is a DPV curve diagram of rutin concentration range of 0.01-20 μmol / L, wherein curves a-o represent DPV curve diagrams of rutin range of 0.01 μmol / L, 0.05 μmol / L, 0.1 μmol / L, 0.3 μmol / L, 0.5 μmol / L, 0.8 μmol / L, 1 μmol / L, 2 μmol / L, 4 μmol / L, 8 μmol / L, 10 μmol / L, 12 μmol / L, 14 μmol / L, 18 μmol / L, and 20 μmol / L, respectively; Figure 7 In the middle, C is the linear relationship between the oxidation peak current and the rutin concentration in the range of 0.0001 to 0.01 μmol / L;

[0103] Figure 7 D in the middle is the linear relationship between the oxidation peak current and the rutin concentration in the range of 0.01 to 20 μmol / L;

[0104] The mechanism is: rutin molecules are oxidized to 3',4'-diquinone structures to generate oxidation peak current, and 3',4'-diquinone can obtain protons and electrons and be reduced to rutin molecules again, thereby generating reduction peak current.

[0105] like Figure 7 As shown in C, in the range of rutin concentration of 0.0001 to 0.01 μmol / L, there are two linear relationships (0.0001 to 0.001 μmol / L and 0.001 to 0.01 μmol / L), and the linear equation of the lower linear range (0.0001 to 0.001 μmol / L) is Ipa = 103682.19c (μmol / L) + 162.49 (γ 2 =0.985), the linear equation in the higher linear range (0.001-0.01 μmol / L) is Ipa=1243.07c(μmol / L)+142.05(γ 2 =0.999); Figure 7 As shown in D, in the range of 0.01 to 20 μmol / L, the linear equation is Ipa = 8.27c (μmol / L) + 128.35 (γ2 =0.996).

[0106] Due to TiO 2 -The huge specific surface area of ​​the PCNF graded nanocomposite provides more adsorption sites for rutin molecules. According to the linear equation in the lower linear range, the detection limit of the electrode obtained in Example 1 is 0.045 nmol / L.

[0107] 8. Determination of rutin content:

[0108] In a PBS electrolyte with pH = 3, the Nafion / Au / TiO prepared in Example 1 was used to 2 -PCN F / CILE composite modified electrode is used as the working electrode, platinum electrode is used as the auxiliary electrode, and saturated calomel electrode is used as the reference electrode to form a three-electrode system;

[0109] Take a piece of compound rutin tablet (Shimao Tianjie Pharmaceutical (Jiangsu) Co., Ltd., rutin content 20 mg / tablet) and grind it, dissolve it in 50 mL of anhydrous ethanol to prepare the sample to be tested;

[0110] Take 0.382mL of rutin ethanol solution and disperse it into 49.618mL of PBS solution with pH=3, and use DPV method to detect the corresponding current value (I) of the sample to be tested, and then Figure 7 Middle C and Figure 7 The corresponding concentration value was obtained from the IC curve of D, and its recovery was determined by the standard addition method.

[0111] The results showed that the quantitative detection of rutin content in the target compound rutin tablets was 20.07 mg / tablet, which was basically consistent with the nominal content (20 mg / tablet), and the recovery rate was between 99.33% and 102.4%, confirming that the modified electrode has good accuracy and practical application value in drug analysis.

[0112] It can be seen from the above examples that the titanium dioxide coated porous carbon nanofiber material prepared in the present invention has a fiber network structure, excellent conductivity and biocompatibility, and can promote the electron transfer of rutin on the surface of the modified electrode; the Nafion / Au / TiO prepared by layered drop coating and electrochemical deposition in the present invention 2 -PCN F / CILE showed a pair of redox peaks with good peak shape in rutin aqueous solution, with a linear detection range of 0.0001-20 μmol / L and a detection limit of 0.045 nmol / L. 2 -PCNF / CILE composite modified electrode) has the advantages of good electrocatalytic oxidation effect, wide linear range, low detection limit and high sensitivity, and can be well used to detect the content of rutin in the target object.

[0113] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a Nafion / Au / TiO2-PCNF / CILE composite modified electrode, characterized in that: The following steps are involved: A solution of porous carbon nanofibers coated with titanium dioxide is coated on a carbon ion liquid electrode to obtain a TiO2-PCNF / CILE electrode; Electrodepositing the TiO2-PCNF / CILE electrode in a gold salt solution to obtain an Au / TiO2-PCNF / CILE electrode; The Nafion ethanol solution is coated on the Au / TiO2-PCNF / CILE electrode to obtain a Nafion / Au / TiO2-PCNF / CILE composite modified electrode.

2. The preparation method according to claim 1, characterized in that: The coating amount of the titanium dioxide coated porous carbon nanofiber on the TiO2-PCNF / CILE electrode is 0.01-0.10 mg / cm 2 .

3. The preparation method according to claim 1, characterized in that: The gold salt solution includes HAuCl4 solution, and the concentration of the gold salt solution is 1.0-3.0 mmol / L.

4. The preparation method according to claim 1, characterized in that: The deposition potential of the electrodeposition is -0.2 to -0.5 V, and the deposition time is 50 to 200 s.

5. The preparation method according to claim 3, characterized in that: The deposition amount of Au on the Au / TiO2-PCNF / CILE electrode is 1.0-5.0 μg / cm 2 .

6. The preparation method according to claim 1, characterized in that: The volume concentration of the Nafion ethanol solution is 3.0-7.0%.

7. The preparation method according to claim 6, characterized in that: The coating amount of Nafion on the Nafion / Au / TiO2-PCNF / CILE composite modified electrode is 0.5-2.0 mg / cm 2 .

8. The Nafion / Au / TiO2-PCNF / CILE composite modified electrode prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the Nafion / Au / TiO2-PCNF / CILE composite modified electrode according to claim 8 in detecting rutin.

10. The use according to claim 9, characterized in that: The method of application comprises the following steps: Using Nafion / Au / TiO2-PCNF / CILE composite modified electrode as the working electrode, in a three-electrode system with PBS buffer solution of pH=3.0 as the electrolyte, the rutin sample was subjected to electrochemical reaction and the rutin content was calculated.

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