CN106290506A - Boron doped graphene gold-supported core plation shell nano composite material modified electrode measures rutin method - Google Patents

Abstract

Boron-doped graphene-supported gold-core-gold-platinum alloy-shell nanocomposite modified electrode for the determination of rutin. Graphene oxide was prepared by Hummers method, and boron-doped graphene (BG) was synthesized by hydrothermal method using graphene oxide as raw material and diboron trioxide as boron source and reducing agent. Nano-gold sol seeds were prepared by Frens' method, and gold-core-gold-platinum alloy-shell nanoparticles (Au@AuPt) were prepared by seed induction method. Using boron-doped graphene with a large specific surface area as a carrier, Au@AuPt nanoparticles were embedded between graphene sheets to obtain boron-doped graphene-supported Au@AuPt nanocomposites. Using the prepared new nanocomposite material to modify the glassy carbon electrode, an electrochemical sensor capable of rapid detection of rutin was successfully constructed. The linear fitting equation of rutin concentration and oxidation peak current was obtained: I _p =6604.1c+8.2044, and the detection limit of rutin was 0.3×10 ^‑12 M.

Description

Boron-doped graphene-supported gold-core gold-platinum alloy shell nanocomposite modified electrode measurement rutin method

technical field

The invention relates to the field of detection methods for active components in tea, in particular to a method for measuring rutin with a boron-doped graphene-loaded gold-core-gold-platinum alloy shell nanocomposite modified electrode.

Background technique

In recent years, more and more attention has been paid to the relationship between free radicals and various diseases. The development of free radical biomedicine has made the search for efficient and low-toxic free radical scavengers - natural antioxidants become a research hotspot in biochemistry and medicine. Oxidation is considered to be the most important mechanism of tea health care and anti-cancer. A large number of research reports have confirmed that polyphenols in tea have various health functions such as anti-oxidation, anti-cancer, anti-mutation, lowering blood fat, lowering blood pressure, sterilization, and anti-inflammatory. It is the most important physiologically active ingredient in tea. As a flavonoid antioxidant substance, rutin has various pharmacological activities such as reducing capillary permeability, anti-inflammatory, anti-allergic, anti-tumor, anti-bacterial, anti-viral and inhibiting aldose reductase. Therefore, establishing a highly sensitive method for detecting rutin is of great significance for food analysis, drug analysis and medical research. At present, the analysis methods of rutin mainly include ultraviolet spectrophotometry, thin layer scanning method, high performance liquid chromatography and capillary electrophoresis. Among these four methods, the first two methods have poor sensitivity and narrow linear range; the latter two methods require more complicated and expensive instruments and equipment. Therefore, it is of great significance to establish a fast and simple analytical method for the detection of the active ingredient rutin in tea.

The rutin molecule contains 4 phenolic hydroxyl groups and has electrochemical activity, so it can be detected by electroanalytical chemical method. Because the electrochemical analysis method has the characteristics of fast detection speed, easy operation, low cost, low detection limit and high sensitivity, a wide linear range can be obtained by electrochemical method detection, and the detection speed is fast, so the electrochemical method is used to detect The active ingredients in tea have a relatively broad application space.

Contents of the invention

In order to solve the problems in the above-mentioned prior art, the object of the present invention is to provide a method for measuring rutin by a boron-doped graphene-supported gold-core-gold-platinum alloy shell nanocomposite modified electrode, aiming to achieve The rapid and effective determination of active ingredients in tea provides a research basis for the development and utilization of rich tea products in Yunnan Province in high-tech fields.

The sensitivity and selectivity of electrochemical sensors mainly depend on the transducer (signal conversion element) and recognizer (sensitive element) on the electrode, where the interface sensing material of the transducer requires high electronic conductivity, high specific surface area and good The catalytic activity of the transducer is to improve the adsorption performance and biocompatibility of the transducer to sensitive materials, reduce the overpotential of the redox reaction, and improve the selectivity and sensitivity of the biosensor. Therefore, the present invention uses boron oxide as the doping material of graphene, introduces electrons or holes into the graphene material, adjusts the electronic structure of graphene, improves its physical and chemical properties, thereby changing the electron transport properties of graphene. More meaningfully, boron-doped point-defect graphene can enhance the interaction between Ag, Au, and Pt metals and graphene, and obtain electrode interface modification materials with high electronic conductivity.

To achieve the above object, the technical solution of the present invention is:

The boron-doped graphene-loaded gold-nucleus-gold-platinum alloy shell nanocomposite modified electrode is a method for determining rutin, and the steps are as follows:

Step 1. Preparation of boron-doped graphene-supported gold-core-gold-platinum alloy-shell nanocomposites

Boron-doped graphene was synthesized by hydrothermal method; Au@AuPt core-shell nanoparticles were prepared by seed growth method; finally, hundreds of core-shell nanoparticles were embedded into boron-doped graphene sheets by ultrasonic technology Between the structures, the boron-doped graphene is further exfoliated into a single-layer or several-layer sheet structure. At the same time, the boron-doped point-defect graphene enhances the adhesion of Au@AuPt core-shell nanoparticles on its surface, eliminating The defect of easy aggregation and deactivation of nanoparticles is eliminated, so as to obtain BG/Au@AuPt electrode interface modification materials with high electronic conductivity;

Step 2. Preparation of electrochemical sensor based on boron-doped graphene-loaded gold-core-gold-platinum alloy-shell nanocomposite material

First, glassy carbon electrodes (GCE) with a diameter of 3 mm were polished on the suede to a mirror surface with 1.0 μm, 0.3 μm and 0.05 μm Al ₂ O ₃ solutions in sequence, and then 1.0M HNO ₃ solution, absolute ethanol and Ultrasonic cleaning in secondary water, and finally drying with high-purity nitrogen; use a pipette gun to take 10 μL of the prepared BG/Au@AuPt and drop-coat it on the surface of the glassy carbon electrode, dry it and save it for later use. The electrode is referred to as BG/Au@AuPt/GCE ;

Step 3. Detection of rutin based on boron-doped graphene-loaded gold-core-gold-platinum alloy-shell nanocomposite modified electrode

The constructed BG/Au@AuPt/GCE was used for the rapid detection of rutin in tea, where the optimum pH of phosphate buffer solution was 4, the enrichment time was 400s, and the enrichment potential was 0.4V; under the optimum experimental conditions Next, 1) The influence of scanning speed on the electrochemical behavior of rutin was investigated, and according to the linear fitting equation of scanning speed and oxidation and reduction peak current values, it was shown that the modified electrode was mainly controlled by the adsorption of rutin; 2) Differential pulse voltammetry was used Rutin was detected, and according to the linear relationship between concentration and oxidation peak current value, the linear range and detection limit of the modified electrode for rutin detection were obtained; After the composite modified electrode continuously scanned 25 cycles in the presence of rutin, the redox current did not decrease significantly, indicating that the doped graphene-loaded core-shell noble metal nanocomposite provided good stability for the sensor, and at the same time, it could be used for a long time. Keep the stable activity and stability of the sensor; 4) the modified electrode shows excellent anti-interference ability when detecting rutin, through the detection of the active components in the tea leaves by the standard addition recovery method, it is concluded that the modified electrode has a positive effect on the rutin in the tea leaves. The active ingredient rutin has a good response and can be used for the detection of actual samples.

Further, in the step 1, the specific preparation method of boron-doped graphene is: take 5mL graphene oxide and 30mL dedistilled water, according to the mass ratio of graphene oxide and boron trioxide is 1:10, 1:20 , 1:25, 1:30 weigh diboron trioxide, and dissolve the weighed diboron trioxide in 20mL distilled water. Mix the graphene oxide solution, de-distilled water, and boron trioxide solution and sonicate for 1 hour, pour into a high-pressure reactor and heat up to 160°C, react for 3 hours, take out the boron-doped graphene and sonicate for 2 hours after cooling, and you can get uniformly dispersed Boron doped graphene.

Further, when preparing boron-doped graphene in the first step, the mass ratio of B ₂ O ₃ to graphene oxide is 1:20.

Further, in the first step, the preparation method of Au@AuPt core-shell nanoparticles is as follows: using the Frens' method to prepare nano-gold sol, put 50mL 0.01wt% HAuCl ₄ solution into a three-necked flask, and install the reflux device , heated to boiling under stirring, quickly added 3mL 38.8mM sodium citrate solution, the solution gradually changed from purple to blue, and finally turned into wine red, indicating that chloroauric acid had been reduced to nano-gold, and continued to boil for about 30 minutes. Cool to room temperature to prepare gold seeds; use the seed induction method, use Au nanoparticles as seeds, take a Erlenmeyer flask, add 2mL gold sol under ice bath conditions, then add 680μL 1mM chloroauric acid and 680μL 1mM chloroplatinic acid, 640μL distilled water, the mixed solution was stirred for at least 2min under ice bath conditions, and finally 660μL sodium borohydride solution (10mM) was evenly and slowly dropped into the above solution with a micro syringe to continue the reaction. The red color gradually changes to purple, indicating that the Au@AuPt nanoparticles have been formed.

Further, in the third step, differential pulse voltammetry was used to investigate the electrochemical behavior of rutin on the modified electrode, and the linear fitting equation of rutin concentration and oxidation peak current was obtained as: I _p =6604.1c+8.2044, The detection limit of rutin was 0.3×10 ^-12 M.

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

The invention discloses a method for determining rutin based on a boron-doped graphene-loaded gold-nucleus-gold-platinum alloy shell nanocomposite modified electrode. The preparation of a chemically modified electrode by the method is a fast and simple method, and the detection method is simple and convenient to operate. The method is quick and low in cost, can effectively and quickly detect the active ingredient rutin in tea, and has the value of popularization and application. At the same time, the method of the present invention can save the cumbersome process of actual sample pretreatment, eliminate the defects of complicated and time-consuming preparation of samples and test samples, and the whole detection and analysis method is simple and convenient, with good reproducibility and high sensitivity of analysis and determination. The content of active ingredients provides a research basis for the development and utilization of rich tea products in Yunnan Province in high-tech fields. The physiologically active ingredients in tea products have anti-oxidation, anti-cancer, anti-mutation, lowering blood fat, lowering blood pressure, sterilization, It is of great significance to study various health care functions and pharmacological mechanisms such as anti-inflammatory.

Description of drawings

Fig. 1 is the XRD pattern of graphene oxide and boron-doped graphene;

Figure 2 is the XRD pattern of boron-doped graphene with different mass ratios.

Figure 3 is the XPS pattern of boron-doped graphene.

Figure 4 is a scanning electron microscope image of boron-doped graphene.

Figure 5 is the XRD patterns of Au and Au@AuPt nanoparticles.

Figure 6 is a scanning electron microscope image of Au@AuPt nanoparticles.

Fig. 7 XRD patterns of boron-doped graphene supported Au@AuPt nanocomposites.

Fig. 8 SEM images of boron-doped graphene supported Au@AuPt nanocomposites.

Fig. 9 is a cyclic voltammetry curve of a blank PBS solution and a PBS solution containing 0.5 μM/L rutin.

The left figure of Fig. 10 is the cyclic voltammetry curve of 0.5 μM/L rutin in PBS with different pH (1-7), and the right figure is the linear fitting figure of rutin peak current and pH.

Figure 11 left is the enrichment potential of 0.4V, enriched at different times (10s, 50s, 100s, 200s, 300s, 350s, 400s, 450s, 600s), the cyclic voltammetry curve of rutin, the right is enriched at different times Curves of current versus time for oxidation peak (b) and reduction peak (a) of post-rutin.

Figure 12. The left figure is the cyclic voltammetry curve of rutin enriched at different potentials (0.1-0.6V) for 400 s, and the right figure is the oxidation peak (b) and reduction peak (a) of rutin enriched at different potentials Curves of current versus enrichment potential.

Figure 13. The cyclic voltammetry curves of rutin at different scanning speeds (10-600mV/s) on the left, and the linear fitting of current and scanning speed on the oxidation peak (b) and reduction peak (a) at different scanning speeds on the right. picture.

Figure 14 is the differential pulse voltammetry curves of different concentrations of rutin on the left, and the linear fitting diagram of the oxidation peak current and concentration of rutin at different concentrations on the right.

Fig. 15 is the cyclic voltammetry curve of 25 consecutive scans of PBS solution containing 0.5 μM/L rutin.

detailed description

The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments:

Test example:

1. Preparation of boron-doped graphene

Experimental Instruments and Experimental Reagents

Experimental instruments: round bottom three-neck flask, stirrer, centrifuge, vacuum filtration pump, suction filtration bottle, electronic analytical balance, pipette gun, drying oven, vacuum drying oven, transmission electron microscope. Autoclave, beaker, ultrasonic cleaner.

Experimental reagents: graphite powder, ice, concentrated H ₂ SO ₄ , KMnO ₄ , 30% H ₂ O ₂ , distilled water, diboron trioxide, graphene oxide.

Preparation of Graphene Oxide

Graphene oxide was prepared according to Hummer's classic method: take _92mL of concentrated _H2SO4 in a _three -necked flask under ice bath conditions, add 2g of graphite powder and 2g of NaNO3 solid mixture into the flask under constant stirring, and then divide 12g of _KMnO4 , fully Stir to mix the reactants well. Then the mixture was transferred to a water bath at 30° C. to 40° C. and stirred for one hour to form a beige paste. Take out the mixed solution and add 160mL of distilled water at room temperature. Vigorous bubbling of the solution can be observed, then the temperature is raised to 85°C-95°C and the stirring is continued for 30 minutes, and then diluted with water to 560mL. Finally, 12 mL of 30% H ₂ O ₂ was slowly added several times, and the solution changed from dark brown to bright yellow. The obtained product was filtered while hot, washed with warm water and centrifuged until neutral.

Cleaning specific steps:

1. Heat water to fully dissolve it after suction filtration while it is hot;

2. Use a centrifuge to centrifuge at a speed of 3000r/d for 1min and discard the impurities in the lower layer;

3. Use a centrifuge to centrifuge at a speed of 8000r/d for 3min to discard the supernatant;

4. Use a centrifuge to centrifuge at a speed of 10000r/d for 5min to discard the upper layer;

5. Use a centrifuge to centrifuge at a speed of 13000r/d for 5 minutes; wash until it is close to neutral, and then prepare graphene oxide.

Preparation of Boron-doped Graphene

Get 5mL graphene oxide and 30mL de-distilled water, according to the mass ratio of graphene oxide and boron trioxide is 1:10, 1:20, 1:25, 1:30 to weigh boron trioxide, the weighed Diboron trioxide was dissolved in 20 mL of distilled water. Mix the graphene oxide solution, de-distilled water, and boron trioxide solution and sonicate for 1 hour, pour into a high-pressure reactor and heat up to 160°C, react for 3 hours, take out the boron-doped graphene and sonicate for 2 hours after cooling, and you can get uniformly dispersed Boron doped graphene.

Experimental Results and Discussion

Figure 1 is the XRD pattern of graphene oxide and boron-doped graphene. It can be seen from the figure that graphene oxide has a diffraction peak at a diffraction angle (2θ) of 10.68°, and the incorporation of boron makes the diffraction peak disappear. , and a diffraction peak appeared at the diffraction angle (2θ) of 24.44°, indicating that graphene oxide has been reduced.

Figure 2 is the XRD pattern of boron-doped graphene with different mass ratios. By mixing B ₂ O ₃ and graphene oxide in different mass ratios, boron-doped graphene with different boron contents can be obtained. It can be seen from Figure 2 that when the mass ratio of B ₂ O ₃ to graphene oxide is 1:25 and 1:30, while the diffraction peak of boron-doped graphene appears, the two diffraction peaks of B ₂ O ₃ It also appears, indicating that B ₂ O ₃ has not completely reacted and there is a surplus, which is due to the addition of too much boron trioxide. However, when the mass ratio of B ₂ O ₃ to graphene oxide is 1:10 and 1:20, only the diffraction peak of boron-doped graphene appears, and there is no diffraction peak of B ₂ O ₃ , so B ₂ O ₃ and graphene oxide The mass ratio of 1:20 is the best mass ratio for preparing boron-doped graphene.

Figure 3 is the XPS pattern of boron-doped graphene. The chemical composition of boron-doped graphene was detected by X-ray photoelectron spectroscopy (XPS). It can be seen from the figure that three strong peaks appeared in the range of 298.48-279.68eV, 545.48-528.68eV, and 196.48-180.68eV. The characteristic peaks assigned to C1s, O1s, and B1s respectively indicate that boron-doped graphene has been successfully prepared.

Figure 4 is a scanning electron microscope image of boron-doped graphene. Boron-doped graphene is disordered, translucent, and wrinkled, and some of the flakes are stacked together to form a multilayer structure. This edge curled wrinkled shape is Due to the defects caused by the doping of boron atoms into the graphene lattice, the graphene surface has many active sites, so boron-doped graphene is partially agglomerated. 2. Preparation of Au@AuPt nanoparticles

Experimental Instruments and Experimental Reagents

Experimental equipment: round bottom three-neck flask, condensing reflux tube, magnetic stirrer, magnetic stirrer, volumetric flask, electronic balance, magnetic stirrer, pipette gun, Erlenmeyer flask, beaker, volumetric flask, petri dish, pipette gun , transmission electron microscope, UV-visible spectrophotometer.

Experimental reagents: trisodium citrate, chloroauric acid, distilled water, chloroplatinic acid, sodium borohydride, distilled water.

Preparation of gold seeds

Prepare nano-gold sol by Frens' method, put 50mL 0.01wt% HAuCl ₄ solution into a three-neck flask, install a reflux device, heat to boiling under stirring, then quickly add 3mL 38.8mM sodium citrate solution, the solution turns from purple to Gradually turn into blue, and finally into wine red, indicating that chloroauric acid has been reduced to nano gold, continue to boil for about 30min, cool to room temperature, and gold seeds can be prepared.

Preparation of Au@AuPt Nanoparticles

Using the seed induction method, use Au nanoparticles as seeds, take an Erlenmeyer flask, add 2mL of gold sol under ice bath conditions, then add 680μL 1mM chloroauric acid and 680μL 1mM chloroplatinic acid, 640μL distilled water, the mixed solution in Stir in an ice bath for at least 2 minutes, and finally drop 660 μL of sodium borohydride solution (10 mM) into the above solution uniformly and slowly with a micro-syringe to continue the reaction. Nanoparticles are formed.

Results and discussion

Figure 5 is the XRD pattern of Au and Au@AuPt nanoparticles. The diffraction angles (2θ) of Au nanoparticles are 38.20°, 44.38°, 64.62° and 77.7°, which belong to Au nanoparticles (111), (200) , (220) and (311) crystal face diffraction peaks, indicating that the prepared gold nanoparticles have a face-centered cubic structure. When the gold-platinum alloy is wrapped on the gold core surface, the diffraction angle (2θ) of Au@AuPt nanoparticles is at 38.36°, 44.58°, 64.74° and 77.86°, and the diffraction angle (2θ) of Au nanoparticles shifts to the right. Preliminary indications that Au@AuPt nanoparticles have been successfully prepared.

Figure 6 is a scanning electron microscope image of Au@AuPt nanoparticles. The nanoparticles with granular structure in the figure are Au@AuPt nanoparticles. The nanoparticles are basically spherical and have an average particle size of about 20nm.

3. Detection of rutin based on boron-doped graphene-loaded gold-core gold-platinum alloy shell nanocomposite electrochemical sensor

Experimental Instruments and Experimental Reagents

Experimental equipment: beaker, volumetric flask, glass rod, pipette gun, ultrasonic cleaner, glass plate, electrochemical workstation, platinum electrode, Ag/AgCl electrode, washing bottle, glassy carbon electrode, chamois leather.

Experimental reagents: distilled water, aluminum oxide nano-polishing powder, potassium ferricyanide solution, sodium dihydrogen phosphate, disodium hydrogen phosphate, standard rutin, tea leaves.

Preparation of boron-doped graphene-supported gold-core-gold-platinum alloy-shell nanocomposites

Boron-doped graphene solution: Au@AuPt nanoparticle solution with a volume ratio of 1:2, put the mixed solution in a beaker and sonicate for 3 hours, and the required temperature should not exceed 35°C to obtain boron-doped graphene-supported gold nuclei Platinum alloy shell nanocomposites.

Figure 7 is the XRD pattern of boron-doped graphene-loaded gold-nuclear gold-platinum alloy shell nanocomposites. The diffraction angle (2θ) is 22.4°, which is the diffraction peak of boron-doped graphene at 38.36°, 44.58°, 64.74° and 77.86° °The diffraction peaks of Au@AuPt nanoparticles appeared, indicating that boron-doped graphene-loaded gold-core-gold-platinum alloy-shell nanocomposites have been successfully prepared.

Fig. 8 SEM image of boron-doped graphene-supported gold-core-gold-platinum alloy-shell nanocomposite. After boron-doped graphene and Au@AuPt nanocomposites are dispersed by ultrasound, Au@AuPt nanoparticles are more uniformly embedded in boron-doped graphene sheets. Due to the embedding of Au@AuPt nanoparticles, boron-doped graphene It was exfoliated into a single-layer sheet structure, which eliminated the agglomeration of boron-doped graphene to a certain extent.

3. Preparation of glassy carbon electrode (BG/Au@AuPt/GCE) modified by boron-doped graphene-supported gold core gold-platinum alloy shell nanocomposite

First, the glassy carbon electrode was polished to a mirror surface on the suede with 1.0 μm, 0.3 μm and 0.05 μm Al ₂ O ₃ solutions in sequence, then ultrasonically cleaned with 1.0M HNO ₃ solution, absolute ethanol and secondary water, and finally cleaned with Blow dry with high-purity nitrogen, and detect by cyclic voltammetry in 10mL 1M potassium ferricyanide solution, the redox peak potential difference is not more than 80mV. If it exceeds, repeat the above steps until it does not exceed 80mV. Finally, 10 μL of the prepared boron-doped graphene-supported Au@AuPt nanocomposite material was drip-coated on the surface of the glassy carbon electrode with a pipette gun, and dried and stored for later use.

Electrochemical Behavior of Modified Electrode for Rutin

Prepare 0.01mM rutin standard sample, phosphate buffered saline solution (PBS) with a pH range of 3-5, take 10mL PBS into the detection bottle, add 500μL 0.01mM rutin standard sample, scan range is 0-0.8V, scan speed is 50mV/s.

Fig. 9 is a cyclic voltammetry curve of a blank PBS solution and a PBS solution containing 0.5 μM/L rutin. For the blank PBS solution, there was no redox peak, but after adding 0.5 μM/L rutin, an obvious redox peak appeared, indicating that BG/Au@AuPt/GCE had a good response to rutin. The electrooxidation mechanism of rutin on the modified electrode can be expressed as: rutin loses a proton to form a monovalent anion, and then the monovalent anion is oxidized to an anion radical, and the anion radical is further oxidized to dehydrogenation through a reversible oxidation process rutin.

Fig. 10 Cyclic voltammetry curves of rutin on different modified electrodes GCE (a), BG/GCE (b), BG/Au@AuPt/GCE (c). It can be seen from the figure that there is no redox peak when the bare electrode detects rutin, indicating that the bare electrode has no response to rutin; while BG/GCE detects rutin, there are obvious redox peaks, when the Au@ After AuPt nanoparticles are embedded in boron-doped graphene, the redox peak of rutin on BG/Au@AuPt/GCE is further increased, indicating that Au@AuPt nanoparticles are embedded in the boron-doped graphene sheet structure, further The boron-doped graphene is exfoliated into a single-layer or several-layer sheet structure, and the boron-doped point-defect graphene enhances the adhesion of Au@AuPt core-shell nanoparticles on its surface, eliminating the easy Due to the defects of aggregation and inactivation, the obtained BG/Au@AuPt electrode interface modification material is an excellent material for detecting rutin.

Effect of different pH on detection of rutin

The left figure in Fig. 11 is the cyclic voltammetry curve of PBS containing 0.5 μM/L rutin at pH=1-7. With the gradual increase of pH, the redox peak current also increases gradually, and the peak potential shifts to the left. When the pH is 4, the peak current is the largest, and then the peak current gradually decreases. It can be concluded that the optimum pH value for detecting rutin is 4.

Effect of different enrichment time on the detection of rutin

The rutin counter electrode is mainly controlled by adsorption, one is the influence of time on adsorption; the other is the influence of potential on adsorption. Therefore, enrichment should be carried out before the determination of rutin by cyclic voltammetry, and the rutin in the PBS buffer solution should be enriched on the electrode surface as much as possible to reduce the error in the determination process. Figure 12 (left figure) is the cyclic voltammetry curve of rutin after enrichment for different time (10-600s) when the enrichment potential is 0.4V, (right figure) is the oxidation peak of rutin after different enrichment time (b ), reduction peak (a) curve of current versus time. With the enrichment time getting longer, the redox peak current gradually increased. When the enrichment time reached 400s, the peak current was the largest, and then showed a downward trend. Therefore, the optimal enrichment time of rutin was 400s.

Effect of Different Enrichment Potentials on Detection of Rutin

Figure 13 left is the cyclic voltammetry curve of rutin enriched for 400s at different enrichment potentials (0.1-0.6V), and the right is the oxidation peak (b) and reduction peak (a) of rutin enriched for 400s at different potentials ) current versus enrichment potential curve. With the continuous increase of the enrichment potential, the redox peak current gradually increases until the enrichment potential is 0.4V, the redox peak current is the largest, and then it shows a downward trend. Therefore, the optimal enrichment potential of rutin is 0.4V.

The Effect of Scanning Speed on the Electrochemical Behavior of Rutin

Figure 14. The cyclic voltammetry curves of rutin at different scan speeds (10-600mV/s) on the left, and the oxidation peak (b) and reduction peak (a) currents and scans of rutin at different scan speeds on the right. Fast linear fit graph. In the left figure, the scanning speed increases from 10mV/s to 600mV/s, and the oxidation peak current increases with the increase of the scanning speed; in the scanning range of 10-600mV/s, the oxidation peak, reduction peak current I _p and the scanning speed υ has a linear relationship, the linear regression equation of the oxidation peak current is I _p =0.0542υ-5.4432, R ² =0.9904, and the linear regression equation of the reduction peak current is I _p =0.0382υ+3.8547, R ² =0.9905, indicating that rutin in The range of scanning speed is adsorption control.

Detection of Rutin by Differential Pulse Voltammetry

The left figure of Fig. 15 is the differential pulse voltammetry curve of different concentrations of rutin, and the right figure is the linear fitting graph of the oxidation peak current and the concentration of rutin with different concentrations. That is, keeping the PBS base solution unchanged, adding different amounts of rutin, the peak currents of different concentrations of rutin can be obtained. According to the relationship between the peak current and the concentration of rutin, the linear regression equation is I _p =6604.1c+8.2044, R ² =0.9955, detection limit: 4×10 ^-12 M.

Modified Electrode Stability

In the process of scanning rutin with cyclic voltammetry, all parameters remained unchanged, and the PBS solution containing 0.5 μM/L rutin was scanned continuously for 25 cycles. With the increase of scanning cycles, the redox peak of rutin appeared The peak position and peak current are basically unchanged, and the cyclic voltammetry curves basically overlap, indicating that the boron-doped graphene-supported gold-core-gold-platinum alloy-shell nanocomposite can be well fixed on the electrode and maintain good catalytic activity. Higher stability.

Detection of actual samples by modified electrodes

Weigh 0.05g of black tea and put it into a beaker for subsequent use. Measure 50mL of distilled water and heat to 80°C, pour it into a beaker containing black tea, heat and boil for 10min, place it at room temperature, and filter. Measure a certain amount of tea, dilute it 100 times and store it for the determination of actual samples. Firstly, the tea stock solution was determined, and then the standard addition was carried out for recovery. The same method was used to measure in parallel three times, and the recovery rate of rutin was 89.26-99.17%, which satisfied the detection of actual samples.

Summarize

Au@AuPt nanoparticles were embedded between boron-doped graphene sheets by ultrasonic technology to obtain boron-doped graphene-supported Au@AuPt nanocomposites. Due to the embedding of Au@AuPt nanoparticles, boron-doped graphene is exfoliated into a structure with fewer layers, which eliminates the effect of boron-doped graphene agglomeration to a certain extent. At the same time, the stability and catalytic performance of Au@AuPt nanoparticles are also improved, and Au@AuPt nanoparticles are firmly attached between the graphene sheets.

An electrochemical sensor based on boron-doped graphene-loaded Au@AuPt core-shell nanocomposites was constructed. By optimizing the pH of the PBS buffer solution, it was found that when pH=4, the redox peak current of rutin was the largest, so the pH was Determination of the optimal pH of rutin. Different enrichment times and different enrichment potentials have a greater impact on the detection of rutin. By examining different enrichment times and enrichment potentials, it can be concluded that the best enrichment time is 400s and the best enrichment potential is 0.4 V. By examining the influence of scanning speed on the electrochemical behavior of rutin, it was concluded that the adsorption of rutin was mainly controlled by the modified electrode. Under the conditions of optimal pH, enrichment time and enrichment potential, rutin was detected by differential pulse voltammetry, and the linear fitting equation of rutin concentration and oxidation peak current was obtained: I _p =6604.1c+8.2044, the detection of rutin The limit is 0.3×10 ^-12 M. Under the optimal detection conditions, 25 consecutive cyclic voltammetry scans were performed on rutin, and it can be concluded that the electrode has good stability and reproducibility. Finally, the modified electrode was used for the detection of rutin in actual samples, and it was concluded that BG/Au@AuPt/GCE had a good response to rutin in tea, which could be used for the detection of rutin in actual samples.

Working principle of the present invention is:

The present invention prepares graphene oxide by Hummers method; then prepares boron-doped graphene by hydrothermal method; uses seed growth method to prepare gold seeds; adopts seed induction method, uses sodium borohydride as reducing agent to combine HAuCl ₄ and H ₂ PtCl ₆ Au@AuPt nanoparticles were prepared by reduction on the surface of gold seeds; boron-doped graphene with a large specific surface area was introduced as a carrier to load Au@AuPt core-shell nanoparticles to obtain boron-doped graphene-supported Au@AuPt nanocomposites; Finally, the new nanocomposite modified glassy carbon electrode was used to detect rutin.

1. Prepare graphene oxide by Hummers method; then prepare boron-doped graphene by hydrothermal method; from the XRD patterns of graphene oxide and boron-doped graphene, it can be seen that boron-doped graphene has a higher diffraction angle than graphene oxide. The diffraction peak of boron-doped graphene appeared at (2θ)24.44°, indicating that it is feasible to choose diboron trioxide as the reducing agent and boron source for preparing boron-doped graphene. In addition, experiments show that the mass ratio of B ₂ O ₃ to graphene oxide is 1:20, which is the best mass ratio for preparing boron-doped graphene. From the XPS diagram of boron-doped graphene, it can be seen that the characteristic peaks of C1s, O1s, and B1s appear at 284.3eV, 533.11eV, and 193.45eV, indicating that boron-doped graphene has been successfully prepared.

2. Prepare nano-gold seeds by Frens' method, add HAuCl ₄ and H ₂ PtCl ₆ to the gold seed solution, and use sodium borohydride as a reducing agent to reduce them on the surface of gold seeds to prepare Au@AuPt nanoparticles. From the XRD pattern of Au@AuPt particles, it can be seen that the diffraction angles (2θ) of Au nanoparticles are 38.20°, 44.38°, 64.62° and 77.7°. According to literature reports, the diffraction angles (2θ) of Pt nanoparticles are at 39.76 °, 46.24°, 67.46° and 81.29°, after wrapping gold-platinum alloy on the surface of the gold core, the diffraction angles (2θ) of Au@AuPt nanoparticles are at 38.36°, 44.58°, 64.74° and 77.86°, compared to the nanometer The diffraction angle (2θ) of the particles shifts to the right, indicating that the gold-core gold-platinum alloy shell nanoparticles have been successfully synthesized. It can be seen from the scanning electron microscope that the average particle size of Au@AuPt particles is about 20nm.

3. Boron-doped graphene-supported Au@AuPt nanocomposites were obtained by ultrasonically mixing boron-doped graphene and Au@AuPt nanomaterials at a ratio of 1:2. According to the XRD pattern, the diffraction angles (2θ) of the nanocomposite are 39.76°, 46.24°, 67.46° and 81.29°, 24.44°, and the diffraction patterns of Au@AuPt core-shell nanoparticles and boron-doped graphene appear at the same time. It can be seen from the scanning electron microscope that the embedding of nanomaterials strips graphene into a single-layer or multi-layer sheet structure, which eliminates the agglomeration of boron-doped graphene to a certain extent, and the core-shell nanomaterials are also firm. adhered between the graphene sheets.

4. Boron-doped graphene-loaded Au@AuPt nanocomposite electrochemical sensor for the detection of rutin. By optimizing the pH value of the PBS solution, the optimal pH for the determination of rutin is 4. Different enrichment time and different enrichment potential have great influence on the detection of rutin. According to the difference of enrichment time and enrichment potential, it can be concluded that the best enrichment time is 400s and the best enrichment potential is 0.4 V. By investigating the influence of different scanning speeds on the electrochemical behavior of rutin, the linear fitting equations of scanning speed and oxidation and reduction peak currents were obtained, indicating that rutin was mainly controlled by adsorption on the surface of the modified electrode. Under the conditions of optimal pH, enrichment time and enrichment potential, differential pulse voltammetry was used to detect rutin, and the linear fitting equation of rutin concentration and oxidation peak current was obtained: I _p =6604.1c+8.2044, rutin The detection limit is 0.3×10 ^-12 M. Under the optimal detection conditions, 25 consecutive cyclic voltammetry scans were performed on rutin, and it was concluded that the modified electrode has good stability and reproducibility. Finally, the rutin in tea was detected by the standard recovery method, and it can be concluded that BG/Au@AuPt/GCE has a good response to rutin in tea, which can be used for the detection of actual samples.

The above is only a specific implementation of the present invention, but the scope of protection of the present invention is not limited thereto, and any changes or replacements that do not come to mind through creative work shall be covered within the scope of protection of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope defined in the claims.

Claims (5)

1. The boron-doped graphene-loaded gold-nucleus-gold-platinum alloy shell nanocomposite modified electrode assay method for rutin is characterized in that the steps are as follows: Step 1. Preparation of boron-doped graphene-supported gold-core-gold-platinum alloy-shell nanocomposites Boron-doped graphene was synthesized by hydrothermal method; Au@AuPt core-shell nanoparticles were prepared by seed growth method; finally, hundreds of core-shell nanoparticles were embedded into the boron-doped graphene sheet structure by ultrasonic technology At the same time, the boron-doped graphene is further exfoliated into a single-layer or several-layer sheet structure, and the boron-doped point-defect graphene enhances the adhesion of Au@AuPt core-shell nanoparticles on its surface, eliminating Nanoparticles are easy to aggregate and deactivate defects, so as to obtain high electronic conductivity electrode interface modification materials based on boron-doped graphene/gold-core-gold-platinum alloy shell nanocomposites; Step 2. Preparation of electrochemical sensor based on boron-doped graphene-loaded gold-core-gold-platinum alloy-shell nanocomposite material First, the glassy carbon electrode GCE with a diameter of 3 mm was polished on the suede to a mirror surface with 1.0 μm, 0.3 μm and 0.05 μm Al ₂ O ₃ solutions in sequence, and then 1.0M HNO ₃ solution, absolute ethanol and secondary Ultrasonic cleaning in water, and finally drying with high-purity nitrogen; use a pipette gun to take 10 μL of the prepared boron-doped graphene-loaded gold-core-gold-platinum alloy shell nanocomposite drop-coated on the surface of the glassy carbon electrode, dry and store for later use. Abbreviated as BG/Au@AuPt/GCE; Step 3. Detection of rutin based on boron-doped graphene-loaded gold-core-gold-platinum alloy-shell nanocomposite modified electrode The constructed BG/Au@AuPt/GCE was used for the rapid detection of rutin, where the optimal pH of phosphate buffer solution was 4, the enrichment time was 400s, and the enrichment potential was 0.4V; under the optimal experimental conditions, 1) The influence of scanning speed on the electrochemical behavior of rutin was investigated. According to the equation obtained by linear fitting of scanning speed and oxidation and reduction peak current values, the modified electrode is mainly controlled by the adsorption of rutin; 2) using differential pulse voltammetry According to the linear relationship between the concentration and the oxidation peak current value, the linear range and detection limit of the modified electrode for rutin were obtained; 3) Boron-doped graphene-loaded gold-core-gold-platinum alloy shell nanocomposites In the presence of rutin, the redox current of the modified electrode did not decrease significantly after 25 continuous scans, indicating that the new nanocomposite material provided good stability for the sensor, and at the same time maintained the stable activity and stability of the sensor for a long time ; 4) The modified electrode has shown excellent anti-interference ability when detecting rutin, and the active ingredient in the tea is detected by the standard addition recovery method, and it is concluded that the modified electrode has a good response to the rutin in the tea, which can be used for testing real samples. 2. boron-doped graphene-loaded gold-nucleus-gold-platinum alloy shell nanocomposite modified electrode method for measuring rutin according to claim 1, is characterized in that, in described step one, the specific preparation method of boron-doped graphene For: take 5mL graphene oxide and 30mL dedistilled water, weigh diboron trioxide according to the mass ratio of graphene oxide and diboron trioxide as 1:10, 1:20, 1:25, 1:30, weigh the The obtained boron trioxide was dissolved in 20 mL of distilled water. Mix graphene oxide, de-distilled water, and diboron trioxide solution and sonicate for 1 hour, transfer to a high-pressure reactor, heat up to 160°C and react for 3 hours, and finally take out the cooled boron-doped graphene and sonicate for 2 hours to obtain Uniformly dispersed boron-doped graphene. 3. boron-doped graphene according to claim 2 loads gold core alloy shell nano-material modification electrode and measures rutin method, it is characterized in that, when preparing boron-doped graphene in described step 1, B ₂ O ₃ and The mass ratio of graphene oxide is 1:20. 4. The boron-doped graphene-loaded gold-nucleus-gold-platinum alloy shell nanocomposite modified electrode method for measuring rutin according to claim 1 is characterized in that, in the step one, the Au@AuPt core-shell type nanoparticle The preparation method is: adopt Frens' method to prepare nano-gold sol, put 50mL 0.01wt% HAuCl ₄ solution into a three-necked flask, install a reflux device, heat to boiling under stirring conditions, then quickly add 3mL 38.8mM sodium citrate solution , the solution gradually changed from purple to blue, and finally turned into wine red, indicating that chloroauric acid has been reduced to nano-gold, and kept boiling for about 30 minutes, and cooled to room temperature to obtain gold seeds; using the seed induction method, the Au Nanoparticles were used as seeds, and 2 mL of gold sol was added under ice bath conditions, then slowly added a mixture of 680 μL 1 mM chloroauric acid and 680 μL 1 mM chloroplatinic acid, and 640 μL distilled water, and the mixed solution was stirred for at least 2 min under ice bath conditions, and finally used 660 μL sodium borohydride solution (10 mM) was evenly and slowly dropped into the above solution with a micro syringe, and the reaction was continued for 40 min. The solution gradually changed from wine red of Au sol to purple red, indicating that Au@AuPt nanoparticles had been formed. 5. boron-doped graphene-loaded gold-nucleus gold-platinum alloy shell nanocomposite modified electrode method for measuring rutin according to claim 1, is characterized in that, in described step 3, adopt differential pulse voltammetry to investigate rutin The electrochemical behavior on the modified electrode, the linear fitting equation of rutin concentration and oxidation peak current is: I _p =6604.1c+8.2044, and the detection limit of rutin is 0.3×10 ^-12 M.