A fast and efficient electrochemical sensor for the detection of baicalin

Abstract

The present invention discloses an electrochemical sensor for rapid and efficient detection of baicalin, belonging to the technical field of electrochemical sensors. The raw materials for preparing the electrochemical sensor for rapid and efficient detection of baicalin include: an electrode and a biochar-black phosphorene-silver nanoparticle composite material; the biochar-black phosphorene-silver nanoparticle composite material is covered on the electrode. The electrochemical sensor prepared by the present invention shows good detection sensitivity and electrocatalytic activity for baicalin. The electrochemical sensor prepared by the present invention has low cost, simple process and easy operation, and the electrochemical sensor has the advantages of rapid and efficient, strong selectivity, good stability and high sensitivity, and can realize quantitative analysis and rapid detection of baicalin.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical sensors, in particular to an electrochemical sensor for rapidly and efficiently detecting baicalin. Background Art

[0002] Flavonoids are a class of polyphenolic compounds found throughout the plant kingdom. Due to their significant impact on human health, they are widely studied in drug development. Baicalin, a representative flavonoid herb, can significantly improve the symptoms of several serious diseases. It has been reported to exhibit antibacterial, cholesterol-lowering, anti-tumor, and free radical scavenging properties. Therefore, establishing an accurate, rapid, sensitive, economical, and effective method for the determination of baicalin in traditional Chinese medicine is crucial.

[0003] Agricultural activities generate a vast amount of agricultural waste annually, which is not properly utilized. Pyrolysis of waste to produce biochar not only achieves waste utilization but also has a positive impact on environmental remediation. With the need to protect the human living environment and address the growing need for new energy sources, biomass utilization is becoming a new research focus. Biomass is a renewable resource, collectively referred to as all growing organic matter. It is widely available, has diverse internal structural properties, and is relatively low-cost, offering enormous potential value. A large amount of waste biomass is generated in agriculture, animal husbandry, the food industry, the chemical industry, and the coal industry, offering promising development prospects and a wide range of applications. Biomass is widely available and requires no new raw materials. Agricultural and forestry waste, plant tissue, animal remains, and organic waste can all serve as raw materials for biochar production. Common biochars include rice husk charcoal, straw charcoal, and wood charcoal. As an electrode material, carbon materials have been a hot topic of research due to their excellent properties, including relatively low cost, abundant and readily available raw materials, good conductivity, large specific surface area, and stable chemical properties. Since the 21st century, most carbon-based materials have been synthesized using fossil fuels such as methane, asphalt, and ethanol as raw materials. Furthermore, the experimental conditions or equipment required for the synthesis process are relatively harsh (e.g., chemical vapor deposition, arc discharge technology, etc.), or some toxic reagents are added during the synthesis of carbon-based materials. These methods use relatively high costs for raw materials and reagents and are harmful to the environment. These methods are not only environmentally friendly and do not adhere to the concept of sustainable development, but also consume a great deal of resources. Therefore, it is particularly necessary to find a carbon precursor that is widely available, easily accessible, low-cost, environmentally friendly, and harmless. Rice husk waste has the advantages of being renewable, widely available, and readily available, making it an ideal carbon precursor. Using these waste biomasses to synthesize carbon electrode materials can not only solve the problem of large amounts of waste biomass being difficult to handle, but also effectively utilize biomass, contributing to the sustainable development goal of turning waste into treasure.

[0004] Black phosphorene (BP) has attracted widespread interest from researchers due to its unique structure, large specific surface area, high carrier mobility, and remarkable photoelectric properties, making it a potential application in optoelectronic devices, biomedicine, catalysis, and energy storage. However, BP is easily converted into oxides and rapidly degrades in oxygen-containing or aqueous environments. The long-term water-oxygen stability of BP has become a key issue that needs to be addressed. Previous studies have shown that almost all electrochemical applications cannot be achieved on pure BP-modified electrodes. Summary of the Invention

[0005] The purpose of the present invention is to provide an electrochemical sensor for rapid and efficient detection of baicalin to solve the problems of the above-mentioned prior art. + The researchers used AgNPs and grew them on the surface of BP to prepare BP-AgNPs, which effectively passivated the BP surface. Rice husk-derived biochar (RHB) (stabilized BP) was then hydrothermally carbonized using rice husk as a carbon source and calcined with phosphoric acid as an activator. BP-AgNPs were then mixed with RHB and an environmentally stable biochar-black phosphorene-silver nanoparticle composite (RHB-BP-AgNPs) was prepared using ultrasound-assisted liquid-phase exfoliation. Coating RHB-BP-AgNPs on electrodes can be used directly as an electrochemical sensing platform to determine baicalin content. The method offers advantages such as simplicity, rapid response, high sensitivity, and excellent stability, making it possible to rapidly detect baicalin on-site and online.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is an electrochemical sensor for rapid and efficient detection of baicalin, wherein the raw materials for preparing the electrochemical sensor include: an electrode and a biochar-black phosphorene-silver nanoparticle composite material;

[0008] The biochar-black phosphorene-silver nanoparticle composite material is covered on the electrode.

[0009] Furthermore, the electrode is a glassy carbon electrode; and the biochar-black phosphorene-silver nanoparticle composite material is a graphene-like layered material black phosphorene stabilized by silver nanoparticles and porous rice husk-derived biochar.

[0010] A second technical solution of the present invention is a method for preparing the electrochemical sensor, comprising the following steps:

[0011] (1) adding silver salt to an organic solvent and dissolving the silver salt solution to obtain a silver salt solution, then adding black phosphorus crystal powder (BP), and performing an ultrasonic treatment under an inert atmosphere (to prepare BP-AgNPs), then adding biochar and sodium citrate solution and performing a second ultrasonic treatment, centrifuging, and precipitating the biochar-black phosphorene-silver nanoparticle composite material (RHB-BP-AgNPs);

[0012] Black phosphorus has reducing properties and can reduce Ag + .

[0013] (2) The biochar-black phosphorene-silver nanoparticle composite material is added to water and dispersed evenly to obtain a suspension, and then the suspension is dropwise coated on the electrode surface. After drying, it is placed in a buffer solution for cyclic voltammetry treatment to obtain the electrochemical sensor (RHB-BP-AgNPs / GCE).

[0014] Furthermore, in step (1), the biochar is rice husk-derived biochar; and the method for preparing the rice husk-derived biochar specifically comprises:

[0015] Step A: mixing rice husks and sodium hydroxide solution, performing a hydrothermal reaction, and then filtering to obtain a filtrate;

[0016] Step B: adding cetyltrimethylammonium bromide (CTAB) to the filtrate to adjust the pH to 9, then adding formaldehyde solution until the suspended matter no longer increases, finally reacting in a water bath, filtering, and collecting the precipitate to obtain a precursor;

[0017] In step C, the precursor and phosphoric acid are mixed and calcined under an inert atmosphere, and then a hydrofluoric acid solution is added to the calcined solid product to react. After the reaction is completed, the solid product is washed and dried to obtain the rice husk-derived biochar (RHB).

[0018] Furthermore, in step A, the mass / volume ratio of the rice husk to the sodium hydroxide solution is 4 g:60 mL; the concentration of the sodium hydroxide solution is 5 wt.%; the temperature of the hydrothermal reaction is 160° C., and the time is 24 h;

[0019] In step B, the mass ratio of the rice husk to cetyltrimethylammonium bromide is 4:1; the temperature of the water bath reaction is 50° C., and the reaction time is 6 hours;

[0020] In step C, the mass ratio of the precursor to phosphoric acid is 1:4; the inert atmosphere is nitrogen; the calcination temperature is 800° C. and the time is 4 hours; and the reaction time is 24 hours.

[0021] Furthermore, in step (1), the silver salt solution has a concentration of 5×10 -3M AgNO3 solution; the organic solvent is N-methylpyrrolidone (NMP); the concentration of the sodium citrate solution is 5×10 -3 M; the time of the first ultrasonic treatment and the second ultrasonic treatment is 5h; the inert atmosphere is nitrogen.

[0022] Furthermore, in step (2), the buffer solution is a PBS buffer solution with a pH value of 7.0 and a concentration of 0.1M.

[0023] The third technical solution of the present invention: an application of the above electrochemical sensor in detecting baicalin.

[0024] Furthermore, the application method specifically includes:

[0025] Ⅰ. Add baicalin to the electrolyte solution and mix well to prepare baicalin solutions of different concentrations;

[0026] II. Connecting the electrochemical sensor according to any one of claims 1 to 2 to a test circuit and immersing the sensor in baicalin solutions of different concentrations, detecting the peak current value of the electrochemical sensor by differential pulse voltammetry, and establishing a standard curve based on the baicalin concentration and peak current value;

[0027] III. Connecting the electrochemical sensor according to any one of claims 1 to 2 to a test circuit and immersing the sensor in a sample to be tested, measuring the peak current value of the sample to be tested, and calculating the concentration of baicalin in the test solution according to a linear regression equation.

[0028] Furthermore, the electrolyte solution is a 0.1 M phosphate buffer solution with a pH of 7.0; the detection range of baicalin is 7 nM to 8 μM, and the detection limit is 5.45 nM.

[0029] The present invention discloses the following technical effects:

[0030] (1) The present invention adopts the ultrasound-assisted liquid phase exfoliation method to prepare a biochar-black phosphorene-silver nanoparticle composite material (RHB-BP-AgNPs) with high environmental stability, and modifies the electrode with RHB-BP-AgNPs to obtain an electrochemical sensor (RHB-BP-AgNPs / GCE), which can realize the electrochemical detection of baicalin.

[0031] (2) The RHB-BP-AgNPs / GCE prepared by the present invention exhibited good detection sensitivity and electrocatalytic activity for baicalin. The electrochemical sensor prepared by the present invention is low-cost, simple in process, and easy to operate. Furthermore, the electrochemical sensor exhibits advantages such as rapidity, high efficiency, strong selectivity, good stability, and high sensitivity, enabling quantitative analysis and rapid detection of baicalin.

[0032] (3) The electrochemical sensor of the present invention can be used to determine the concentration of baicalin and the content of baicalin in Qingkailing granules. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 Scanning electron micrographs of BP-AgNPs, RHB, and RHB-BP-AgNPs prepared in the present invention, wherein A represents BP-AgNPs, B represents RHB, and C represents RHB-BP-AgNPs;

[0035] Figure 2 The full XPS spectra of RHB, BP-AgNPs and RHB-BP-AgNPs prepared in the present invention;

[0036] Figure 3 High-resolution XPS spectra of Ag3d (A), P2p (B) and O1s (C) of BP-AgNPs prepared in the present invention, and high-resolution XPS spectra of Ag3d (D), P2p (E) and O1s (F) of RHB-BP-AgNPs;

[0037] Figure 4 Cyclic voltammetric responses of the glassy carbon electrode, BP-AgNPs / GCE, RHB / GCE, and the electrochemical sensor prepared in Example 1 of the present invention to 5.0 μM baicalin;

[0038] Figure 5 The results of detecting baicalin using the electrochemical sensor prepared in Example 1 of the present invention are shown in Figure A, where A is the DPV (differential pulse voltammetry) response diagram of baicalin at different concentrations, and B is the related linear fitting equation diagram;

[0039] Figure 6 This is a graph showing the repeatability, reproducibility, and long-term stability of the RHB-BP-AgNPs composite material prepared in the present invention, where A represents repeatability, B represents reproducibility, and C represents long-term stability;

[0040] Figure 7 This is a diagram showing the specificity investigation results of the electrochemical sensor prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0041] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0042] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0043] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0044] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the present invention. The present description and examples are intended to be illustrative only.

[0045] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0046] Phosphorene (BP) is easily converted into oxides and rapidly degrades in oxygen-containing or aqueous environments. This results in a decrease in the electrocatalytic activity of BP in electrocatalytic reactions. Based on this, the present invention provides an electrochemical sensor for the rapid, efficient, and sensitive detection of baicalin. First, a two-dimensional silver nanoparticle-modified BP (BP-AgNPs) was prepared, and then phosphoric acid-activated rice husk-derived biochar was composited as an electrochemical sensing platform. Baicalin was measured directly in a phosphate-supported electrolyte solution using RHB-BP-AgNPs as an electrochemical sensor.

[0047] Preparation of metal compound modified black phosphorene (BP-AgNPs):

[0048] Take 10mL N-methylpyrrolidone (NMP) and add AgNO3 solid to make the concentration of 5×10 -3M of AgNO3 solution is placed in a round-bottom flask, and then the bulk of black phosphorus crystals is placed in a vacuum bag, crushed into a fine powder, and 5 mg of black phosphorus crystal powder is taken and transferred to the above-mentioned round-bottom flask. Under the protection of nitrogen, an ultrasonic machine is used and continuous ultrasonic treatment is ensured in an ice-water bath for 10 hours. Then, the prepared dispersion is quickly transferred to a centrifuge tube, sealed and kept away from light for standby use. Finally, centrifuge at 12000 rpm for 30 minutes to remove NMP, and obtain the lower precipitate, which is metal compound-modified black phosphorus ene (BP-AgNPs), as shown in the SEM picture. Figure 1 .

[0049] Example 1

[0050] A method for preparing an electrochemical sensor for rapid and efficient detection of baicalin:

[0051] (1) 4 g of rice husk was used as a carbon source, 60 mL of 5 wt.% sodium hydroxide solution was added, and the mixture was hydrothermally reacted at 160 ° C for 24 h. The obtained solution was filtered to obtain a filtrate; 1.0 g of hexadecyltrimethylammonium bromide (CTAB) was added to the filtrate, and then the pH was adjusted to 9 with acetic acid. Then, formaldehyde solution was added until the yellow-brown suspended matter in the solution no longer increased. Then, the mixture was reacted in a water bath at 50 ° C for 6 h, and then filtered with ethanol and water, washed, and dried to obtain a precursor; the precursor and phosphoric acid were mixed in a mass ratio of 1:4, and calcined at a high temperature under a nitrogen atmosphere (calcination temperature was 800 ° C, time was 4 h) to obtain a solid product; finally, 45 mL of 10 wt.% hydrofluoric acid solution was added to the solid product, and the mixture was reacted at room temperature for 24 h. After washing, filtering, and drying, rice husk-derived biochar (RHB) was obtained. The SEM image is shown in FIG. Figure 1 .

[0052] (2) Take 10 mL of N-methylpyrrolidone (NMP) and add AgNO3 solid to a concentration of 5×10 -3 A 100 M AgNO3 solution was placed in a round-bottom flask. Large black phosphorus crystals were then placed in a vacuum bag and crushed into a fine powder. 5 mg of the black phosphorus crystal powder was then transferred to the round-bottom flask. Under nitrogen protection, an ultrasonicator was used and continuous sonication was performed in an ice-water bath for 5 h (to obtain BP-AgNPs). Subsequently, 10 mg of rice husk-derived biochar and solid sodium citrate were added to the round-bottom flask to a concentration of 5 × 10 -3 M, continue ultrasonication for 5 h to obtain a dispersion; the dispersion was quickly transferred to a centrifuge tube, sealed and stored in a dark place, and finally centrifuged at 12000 rpm for 30 min to remove NMP. The lower precipitate was obtained, which was the biochar-black phosphorene-silver nanoparticle composite material (RHB-BP-AgNPs), and the SEM image was shown in Figure 1.

[0053] (3) The RHB-BP-AgNPs prepared in step (2) were dispersed in ultrapure water and evenly dispersed by ultrasonication to obtain a RHB-BP-AgNPs suspension with a concentration of 1 mg / mL. 5 μL of the RHB-BP-AgNPs suspension was dropwise coated on the surface of a clean glassy carbon electrode with a diameter of 3 mm. After drying, a glassy carbon electrode modified with a RHB-BP-AgNPs film was obtained.

[0054] (4) The glassy carbon electrode modified with RHB-BP-AgNPs film was placed in PBS buffer (sodium dihydrogen phosphate / disodium hydrogen phosphate system, concentration of 0.1 M) with a pH value of 7.0, and cyclic voltammetry was used for detection (scan rate 100 mV / s; number of scans: 4; sample interval 0.001 V; rest time: 2 s) to obtain the RHB-BP-AgNPs / GCE electrochemical sensor.

[0055] Effect Example 1

[0056] The BP-AgNPs prepared in the present invention and the RHB and RHB-BP-AgNPs prepared in Example 1 of the present invention were observed by scanning electron microscopy. Figure 1 , Figure 1 A is BP-AgNPs, B is RHB, and C is RHB-BP-AgNPs.

[0057] from Figure 1 It can be seen that black phosphorene (BP) presents a flake-like structure with local wrinkles ( Figure 1 A); Rice husk-derived biochar (RHB) produces a large number of pore structures, which is conducive to the migration and diffusion of ions ( Figure 1 B); When silver nanoparticles and RHB are introduced at the same time, RHB and AgNPs are co-loaded on the surface of ultrathin BP nanosheets ( Figure 1 C), and a BP nanohybrid with excellent catalytic performance and high water and oxygen stability was obtained. The above results show that RHB-BP-AgNPs has been successfully constructed ( Figure 1 C).

[0058] In addition, the specific components of BP-AgNPs, RHB and RHB-BP-AgNPs were analyzed by XPS. Figure 2 .

[0059] from Figure 2 As can be seen, the four main elements of O, Ag, P, and C were observed in the XPS overall spectrum of RHB-BP-AgNPs, indicating the successful composite of RHB and BP-AgNPs.

[0060] In order to further analyze the elemental state, the fine spectra of each element were studied, and the results are shown in Figure 3 .

[0061] Figure 3 A is the Ag3d spectrum of BP-AgNPs, where a pair of peaks at 368.23eV and 374.23eV can be clearly observed, indicating the generation of elemental silver. Correspondingly, a pair of peaks is also observed in the Ag3d spectrum of RHB-BP-AgNPs. Figure 3 E), four peaks were observed at 129.5 eV, 130.6 eV, 133.4 eV, and 134.3 eV. The characteristic peaks at 129.5 eV and 130.6 eV correspond to P 2p3 / 2 and P 2p1 / 2 of P=P bonds, respectively, which are typical characteristics of BP crystals. The peaks at 133.4 eV and 134.3 eV correspond to POP and OPO, respectively, attributed to the binding of some P atoms on the BP surface with oxygen to form a phosphorus-oxygen mixture, PxOy. Furthermore, compared to the BP-AgNPs composite, the P2p and Ag3d peak positions of the RHB-BP-AgNPs were slightly shifted to higher energies, indicating a strong interaction between BP-AgNPs and RHB. These results further demonstrate the successful construction of the RHB-BP-AgNPs composite.

[0062] Effect Example 2

[0063] The glassy carbon electrode (GCE), BP-AgNPs / GCE, RHB / GCE, and the electrochemical sensor prepared in Example 1 were used to detect baicalin (5.0 μM) by cyclic voltammetry. The detection responsiveness of different modified electrodes to baicalin was tested. The results are shown in Table 1. Figure 4 .

[0064] Preparation of BP-AgNPs / GCE: The BP-AgNPs prepared by the above method were dispersed in ultrapure water and evenly dispersed by ultrasonication to obtain a BP-AgNPs suspension with a concentration of 1 mg / mL. 5 μL of the BP-AgNPs suspension was dropwise coated on the surface of a clean glassy carbon electrode with a diameter of 3 mm and dried to obtain BP-AgNPs / GCE.

[0065] Preparation of RHB / GCE: The RHB prepared in Example 1 was dispersed in ultrapure water and evenly dispersed by ultrasonication to obtain an RHB suspension with a concentration of 1 mg / mL. 5 μL of the RHB suspension was dropwise coated on the surface of a clean glassy carbon electrode with a diameter of 3 mm and dried to obtain RHB / GCE.

[0066] from Figure 4It can be seen that the electrochemical sensor prepared in Example 1 can respond to extremely low concentrations of baicalin compared with BP-AgNPs / GCE, RHB / GCE and bare GCE, and its detection sensitivity is better than BP-AgNPs / GCE, RHB / GCE and bare GCE.

[0067] Effect Example 3

[0068] Detection of baicalin concentration

[0069] Baicalin was added to a phosphate buffer solution (0.1 M phosphate buffer at pH 7.0) to obtain mixed test solutions with different baicalin concentrations (7 nM, 50 nM, 0.1 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1.0 μM, 2.0 μM, 3.0 μM, 3.5 μM, 4.0 μM, 4.5 μM, 5.0 μM, 5.5 μM, 6.0 μM, 6.5 μM, 7.0 μM, 7.5 μM, and 8.0 μM). The electrochemical sensor prepared in Example 1 was connected to a test circuit and immersed in the mixed test solution. The oxidation peak current value of the sensor was detected by differential pulse voltammetry. A standard curve was established with the baicalin concentration as the abscissa (in μM) and the oxidation peak current value as the ordinate (in μA): I = 13.7612C + 0.7520 (R 2 =0.9986, 7.0nM~8.0μM), the results are shown in Figure 5 .

[0070] Figure 5 A is the DPV (differential pulse voltammetry) response diagram of the electrochemical sensor prepared in Example 1 detecting different concentrations of baicalin, and B is the related linear fitting equation diagram.

[0071] from Figure 5 It can be seen that the electrochemical sensor prepared by the present invention has a good linear relationship with baicalin, and has a wide linear range (7.0nM~8.0μM), high sensitivity and low detection limit (5.45nM), which fully demonstrates that the electrochemical sensor can successfully detect baicalin of unknown concentration.

[0072] Effect Example 4

[0073] Regarding the stability evaluation of the sensor for detecting baicalin, the repeatability ( Figure 6 A) The RHB-BP-AgNPs / GCE was tested for 35 consecutive times in a phosphate buffer solution (0.1M, pH=7) containing 5 μM baicalin. Figure 6B) Seven different glassy carbon electrodes were modified with RHB-BP-AgNPs materials to obtain the corresponding RHB-BP-AgNPs / GCE. The cyclic voltammetry method was used to detect baicalin in a phosphate buffer solution (0.1M, pH=7) containing 5μM baicalin. The results showed that Figure 6 A-B show that the calculated relative standard deviations (RSDs) are 0.95% and 2.11%, respectively. The above data indicate that the prepared electrochemical sensor has good stability for the determination of baicalin. In addition, in order to study the long-term storage stability of the RHB-BP-AgNPs nanocomposite at room temperature, the modified electrode was stored at room temperature and tested once a day for 16 days. Figure 6 It can be seen from C that the oxidation peak current of the modified electrode remains above 92% of the initial peak value, indicating that the prepared RHB-BP-AgNPs nanocomposite has good cycling stability and long-term stability in oxygenated aqueous solution.

[0074] Effect Example 5

[0075] The specificity of the electrochemical sensor prepared in Example 1 was investigated: the changes in the percentage of oxidation peak current of baicalin before and after the addition of interfering substances were investigated. The specific results are shown in Figure 7 .

[0076] The specific method is as follows: 50 times the concentration (100 μM) of copper chloride, ascorbic acid, chrysin, ferric sulfate, calcium chloride, magnesium chloride, cadmium nitrate and naringin were added to 5 mL of phosphate buffer solution (0.1 M, pH = 7) containing 2 μM baicalin to obtain a test solution containing different interfering substances. Baicalin was detected by cyclic voltammetry to test the effects of different interfering substances on the detection response of baicalin. The results are shown in Figure 7 .

[0077] from Figure 7 It can be seen that after adding 50-fold concentrations of copper chloride, ascorbic acid, chrysin, ferric sulfate, calcium chloride, magnesium chloride, cadmium nitrate and naringin to a phosphate buffer solution (0.1 M, pH = 7) containing 2 μM baicalin, the oxidation peak current percentage of baicalin did not change significantly, thus eliminating the interference of some common ions and flavonoids.

[0078] Effect Example 6

[0079] The accuracy of the electrochemical sensor prepared in Example 1 in detecting the concentration of baicalin was investigated: Qingkailing granules were used as samples and diluted with phosphate buffer solution (0.1 M, pH = 7.0) to a solution containing a baicalin concentration of 0.1 μM. The standard addition method was used, and then different concentrations of baicalin standard solutions were added to make the system become 1.0 μM and 5.0 μM. The above solutions were detected and analyzed using the sensor prepared in Example 1. The results are shown in Table 1.

[0080] Table 1

[0081]

[0082] As shown in Table 1, the accuracy of the above detection is between 95.4% and 104.6%, and the relative standard deviation is between 1.27% and 2.13%, indicating that the sensor constructed in the present invention is feasible for the detection and analysis of actual baicalin samples.

[0083] In summary, the electrochemical sensor of the present invention can not only successfully detect baicalin, but also has the characteristics of high sensitivity, rapid detection, and good stability. The electrochemical sensor of the present invention can be used to determine the concentration of baicalin and the content of baicalin in Qingkailing granules; the preparation cost of the electrochemical sensor of the present invention is low, the process is simple, and the operation is easy.

[0084] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. An electrochemical sensor for rapid and efficient detection of baicalin, characterized in that: The raw materials for preparing the electrochemical sensor include: electrodes and biochar-black phosphorene-silver nanoparticle composite materials; The biochar-black phosphorene-silver nanoparticle composite material is covered on the electrode; The biochar-black phosphorene-silver nanoparticle composite material is a graphene-like layered material black phosphorene stabilized by silver nanoparticles and porous rice husk-derived biochar; The preparation method of the electrochemical sensor comprises the following steps: (1) adding silver salt to an organic solvent and dissolving the silver salt solution to obtain a silver salt solution, then adding black phosphorus crystal powder, performing an ultrasonic treatment under an inert atmosphere, then adding biochar and sodium citrate solution to perform a second ultrasonic treatment, centrifuging, and precipitating to obtain the biochar-black phosphorene-silver nanoparticle composite material; (2) The biochar-black phosphorene-silver nanoparticle composite material is added to water and dispersed evenly to obtain a suspension, and then the suspension is dropwise coated on the surface of the electrode, dried, and placed in a buffer solution for cyclic voltammetry treatment to obtain the electrochemical sensor.

2. The electrochemical sensor according to claim 1, wherein The electrode is a glassy carbon electrode.

3. The electrochemical sensor according to claim 1, wherein In step (1), the biochar is rice husk-derived biochar; the preparation method of the rice husk-derived biochar specifically comprises: Step A: mixing rice husks and sodium hydroxide solution, performing a hydrothermal reaction, and then filtering to obtain a filtrate; Step B: adding cetyltrimethylammonium bromide to the filtrate to adjust the pH to 9, then adding formaldehyde solution until the suspended matter no longer increases, finally reacting in a water bath, filtering, and collecting the precipitate to obtain a precursor; In step C, the precursor and phosphoric acid are mixed, calcined under an inert atmosphere, and then a hydrofluoric acid solution is added to the calcined solid product to react. After the reaction is completed, the solid product is washed and dried to obtain the rice husk-derived biochar.

4. The electrochemical sensor according to claim 3, characterized in that In step A, the mass / volume ratio of the rice husk to the sodium hydroxide solution is 4 g:60 mL; the concentration of the sodium hydroxide solution is 5 wt.%; the temperature of the hydrothermal reaction is 160° C., and the time is 24 h; In step B, the mass ratio of the rice husk to cetyltrimethylammonium bromide is 4:1; the temperature of the water bath reaction is 50° C., and the reaction time is 6 hours; In step C, the mass ratio of the precursor to phosphoric acid is 1:4; the inert atmosphere is nitrogen; the calcination temperature is 800° C. and the time is 4 hours; and the reaction time is 24 hours.

5. The electrochemical sensor according to claim 1, wherein In step (1), the organic solvent is N-methylpyrrolidone; the silver salt solution has a concentration of 5×10 -3 M AgNO3 solution; the concentration of the sodium citrate solution is 5×10 -3 M; the time of the first ultrasonic treatment and the second ultrasonic treatment is 5h.

6. The electrochemical sensor according to claim 1, characterized in that In step (2), the buffer solution is a PBS buffer solution with a pH value of 7.0 and a concentration of 0.1 M.

7. Use of the electrochemical sensor according to any one of claims 1 to 6 in detecting baicalin.

8. The use according to claim 7, characterized in that The application method specifically includes: Ⅰ. Add baicalin to the electrolyte solution and mix well to prepare baicalin solutions of different concentrations; II. Connecting the electrochemical sensor according to any one of claims 1 to 6 to a test circuit and immersing the sensor in baicalin solutions of different concentrations, detecting the peak current value of the electrochemical sensor by differential pulse voltammetry, and establishing a standard curve based on the baicalin concentration and peak current value; III. Connecting the electrochemical sensor according to any one of claims 1 to 6 to a test circuit and immersing the sensor in a sample to be tested, measuring the peak current value of the sample to be tested, and calculating the concentration of baicalin in the test solution according to a linear fitting equation.

9. The use according to claim 8, characterized in that The electrolyte solution is a 0.1M phosphate buffer solution with a pH of 7.0; the detection range of baicalin is 7nM to 8μM, and the detection limit is 5.45nM.

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