Gr / pdda / pdnp electrochemical sensing material, preparation method and application thereof

Abstract

The application relates to the technical field of electrochemical sensing material preparation, in particular to a GR / PDDA / PdNPs electrochemical sensing material, a preparation method and application thereof, wherein PDDA and palladium chloride are sequentially added into a graphene oxide suspension, NaBH4 solution is added after uniform stirring, the temperature is increased to 40-60 DEG C, and stirring reaction is carried out for 5-7 hours; after completion, cooling is carried out; the product is centrifuged, washed and dried to obtain the GR / PDDA / PdNPs electrochemical sensing material; the electrochemical sensing material is uniformly drop-coated on the surface of a glassy carbon electrode to prepare a GR / PDDA / PdNPs / GCE electrochemical sensor, and the electrochemical sensor can be used for detecting the content of barnidipine; and the application also optimizes the conditions for detecting the content of barnidipine; the GR / PDDA / PdNPs / GCE electrochemical sensor has the advantages of high detection sensitivity, good reproducibility, strong stability, low manufacturing cost and the like when detecting the content of barnidipine.

Description

Technical Field

[0001] This invention relates to the field of electrochemical sensing material preparation technology, specifically a GR / PDDA / PdNPs electrochemical sensing material, its preparation method, and its application. Background Technology

[0002] Hypertension, as one of the major chronic diseases threatening public health worldwide, has become a core challenge in the prevention and control of cardiovascular diseases due to its high incidence and harmfulness. In clinical treatment, selecting drugs that combine long-acting antihypertensive, anti-anginal, and cardiovascular protective effects is crucial. Barnidipine, as a second-generation dihydropyridine calcium channel modulator, achieves stable and sustained blood pressure reduction while significantly improving myocardial oxygen supply and demand balance and protecting vascular endothelial function, making it an ideal choice for comprehensive hypertension treatment.

[0003] Accurate monitoring of drug active ingredients is crucial for ensuring the safety and efficacy evaluation of clinical medications. Traditional detection methods, such as ultra-high performance liquid chromatography-mass spectrometry, ultraviolet spectrophotometry, and gas chromatography, while possessing high sensitivity and specificity, have limitations such as high instrument costs, complex sample preparation, and long detection cycles, making them unsuitable for rapid on-site analysis. In contrast, electrochemical sensing technology, with its advantages of ease of operation, rapid response, low cost, and ease of miniaturization, provides a new technological approach for drug analysis.

[0004] Two-dimensional nanomaterials, such as graphene (GR), are unique in their sp... 2 The hybrid honeycomb lattice structure, possessing excellent conductivity, mechanical strength, and a large specific surface area, makes it an ideal carrier for constructing high-performance electrochemical sensors. When combined with palladium nanoparticles (PdNPs), the synergistic effect between the two can further optimize the interfacial electron transport efficiency: the high catalytic activity and strong adsorption capacity of palladium nanoparticles can effectively enrich target molecules, while the excellent conductivity of graphene can accelerate charge transfer and improve the sensor's detection performance.

[0005] Currently, there are few reports on the detection of barnidipine content. Yang Guang et al. used high performance liquid chromatography (HPLC) at a detection wavelength of 236 nm to determine the content of barnidipine hydrochloride and related substances. However, HPLC is costly, complex to operate, and requires strict sample pretreatment, which presents many inconveniences. Summary of the Invention

[0006] To address the above problems, this invention provides a GR / PDDA / PdNPs electrochemical sensing material, its preparation method, and its applications. Using graphene oxide as the base material and PDDA (polydiallyldimethylammonium chloride) as both a reducing agent and a dispersant, along with palladium nanoparticles, a GR / PDDA / PdNPs electrochemical sensing material is prepared. This material is then uniformly drop-coated onto the surface of a treated glassy carbon electrode to fabricate a GR / PDDA / PdNPs / GCE electrochemical sensor. This sensor can be applied to the determination of barnidipine content. Furthermore, this invention optimizes the conditions for detecting barnidipine content. The GR / PDDA / PdNPs / GCE electrochemical sensor exhibits advantages such as high detection sensitivity, good reproducibility, strong stability, and low manufacturing cost when detecting barnidipine content.

[0007] One objective of this invention is to provide a method for preparing GR / PDDA / PdNPs electrochemical sensing materials, which specifically includes the following steps:

[0008] (1) Graphene oxide was ultrasonically dispersed in distilled water to prepare a 1 mg / mL graphene oxide suspension;

[0009] (2) A certain amount of PDDA is slowly added to the graphene oxide suspension obtained in step (1), and stirred for 1-2 h. Then palladium chloride is added to it, and stirring is continued for 1-2 h to obtain a mixture. The mass fraction of PDDA is 35%, and the volume ratio of its added volume to the volume of the graphene oxide suspension is 1:(25-50).

[0010] (3) Add NaBH4 solution dropwise to the mixture obtained in step (2), stir until homogeneous, heat the mixture to 40~60℃, stir at this temperature for 5~7 h, and then let it cool naturally to room temperature.

[0011] (4) Centrifuge the product cooled in step (3), wash the separated solid with distilled water until the pH of the supernatant after washing is 7.0, and dry the washed solid in a drying oven at 60~70℃ for 20~24 h to obtain GR / PDDA / PdNPs electrochemical sensing material.

[0012] In the aforementioned method for preparing GR / PDDA / PdNPs electrochemical sensing materials, the ratio of the mass of palladium chloride added to the mass of graphene oxide in step (1) is 1:(9~10).

[0013] In the aforementioned method for preparing GR / PDDA / PdNPs electrochemical sensing materials, the concentration of the NaBH4 solution is 1 mg / mL, and the volume ratio of its added volume to the volume of the graphene oxide suspension obtained in step (1) is 1:(20~30).

[0014] Another object of the present invention is to provide an electrochemical sensing material of GR / PDDA / PdNPs prepared according to the aforementioned preparation method.

[0015] Another object of the present invention is to provide an application of the aforementioned GR / PDDA / PdNPs electrochemical sensing material in the detection of barnidipine content. Specifically, the GR / PDDA / PdNPs electrochemical sensing material is ultrasonically dispersed in distilled water to obtain a GR / PDDA / PdNPs dispersion. 5-7 μL of the GR / PDDA / PdNPs dispersion is uniformly dropped onto the surface of a treated glassy carbon electrode and allowed to air dry naturally to obtain a GR / PDDA / PdNPs / GCE electrochemical sensor. This GR / PDDA / PdNPs / GCE electrochemical sensor can be used to detect barnidipine content.

[0016] Furthermore, the processing method for glassy carbon electrodes includes: mechanically polishing the bare glassy carbon electrode (GCE) for surface treatment, then ultrasonically washing it sequentially with anhydrous ethanol and ultrapure water, and finally drying it with nitrogen gas for later use.

[0017] In the above applications, as a preferred option, the concentration of the GR / PDDA / PdNPs dispersion is 1 mg / mL.

[0018] In the above applications, as a preferred option, the supporting electrolyte used by the GR / PDDA / PdNPs / GCE electrochemical sensor for detecting barnidipine content is an acetate-sodium acetate buffer solution with a pH of 6.8 to 7.2, and the enrichment time is 140 to 160 s.

[0019] In the above applications, as a preferred method, the linear range for barnidipine content determination is 4.0 × 10⁻⁶. -7 ~2.0×10 -5 mol / L, detection limit is 1.3×10 -7 mol / L.

[0020] Compared with existing technologies, this invention has significant advantages and beneficial effects. Through the above technical solution, this invention achieves considerable technological advancement and practicality, and has broad application value, possessing at least the following advantages:

[0021] This invention uses graphene oxide as the base material and PDDA (polydiallyldimethylammonium chloride) as a reducing agent and dispersant, while also doping with palladium nanoparticles, to prepare a GR / PDDA / PdNPs electrochemical sensing material. This electrochemical sensing material is then uniformly drop-coated onto the surface of a treated glassy carbon electrode to prepare a GR / PDDA / PdNPs / GCE electrochemical sensor, which can be applied to the determination of barnidipine content. Compared to the GR / PDDA / GCE electrode and the bare GCE electrode, the GR / PDDA / PdNPs / GCE electrochemical sensor exhibits better electrochemical response and sensitivity. Using a saturated calomel electrode as the reference electrode, a platinum wire electrode as the counter electrode, and GR / PDDA / PdNPs / GCE as the working electrode, a three-electrode system was formed, optimizing the conditions for using the GR / PDDA / PdNPs / GCE electrochemical sensor to determine barnidipine content. Under preferred conditions, when this GR / PDDA / PdNPs / GCE electrochemical sensor is used to determine barnidipine content, at 4.0 × 10⁻⁶... -7 ~2.0×10 -5 Within the concentration range of mol / L, the peak current showed a linear relationship with the concentration of barnidipine, and the detection limit was 1.3 × 10⁻⁶. -7 mol / L. The preparation process of this invention is simple, and the raw materials used are green and environmentally friendly. The electrochemical sensor made of the prepared GR / PDDA / PdNPs electrochemical sensing material has the advantages of high detection sensitivity, good reproducibility, strong stability and low manufacturing cost for the determination of barnidipine content, and can be used to determine the barnidipine content in actual samples. Attached Figure Description

[0022] Figure 1 These are transmission electron micrographs of graphene (a) and the GR / PDDA / PdNPs electrochemical sensing material prepared in Example 1 (b).

[0023] Figure 2 The images show X-ray diffraction patterns of graphene oxide (a) and the GR / PDDA / PdNPs electrochemical sensing material prepared in Example 1 (b).

[0024] Figure 3 These are the cyclic voltammetry curves of potassium ferricyanide on the GR / PDDA / PdNPs / GCE electrode (a), GR / PDDA / GCE electrode (b), and GCE electrode (c) prepared in Example 1.

[0025] Figure 4 These are the AC impedance curves of K3Fe(CN)6 / K4Fe(CN)6 on the GR / PDDA / PdNPs / GCE electrode (a), GR / PDDA / GCE electrode (b), and GCE electrode (c) prepared in Example 1.

[0026] Figure 5 The figures show the cyclic voltammetry curves of barnidipine in different supporting electrolyte solutions, where a is citrate-sodium citrate buffer solution, b is PBS buffer solution, c is BR buffer solution, and d is acetate-sodium acetate buffer solution.

[0027] Figure 6 This is a linear sweep voltammetric curve of barnidipine in acetate-sodium acetate buffer solutions at different pH values.

[0028] Figure 7 The linear sweep voltammetry curves of the GR / PDDA / PdNPs / GCE electrode prepared in Example 1 in barnidipine solutions of different concentrations are shown.

[0029] Figure 8 yes Figure 7 Enlarged view of the inner illustration. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The present invention will be described in detail below with reference to specific embodiments. Unless otherwise specified, all conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Raw materials and reagents whose manufacturers are not specified are all commercially available products. All operations without specified temperatures are conducted at room temperature.

[0032] Example 1

[0033] (1): Weigh 90 mg of graphene oxide and place it in 90 mL of distilled water and ultrasonically disperse for 2 h to prepare a 1 mg / mL graphene oxide suspension;

[0034] (2): 2 mL of 35% PDDA (polydiallyldimethylammonium chloride) was slowly added to the graphene oxide suspension obtained in step (1), stirred for 1 h, and then 9 mg of palladium chloride was added to it and stirred for another 1 h to obtain a mixture.

[0035] (3): Add 3 mL of 1 mg / mL NaBH4 solution dropwise to the mixture obtained in step (2), stir until homogeneous, heat the mixture to 40°C, stir at this temperature for 5 h, and then cool naturally to room temperature;

[0036] (4): The product cooled in step (3) is centrifuged and separated. The separated solid is washed with distilled water 3 to 5 times until the pH of the supernatant after washing is 7.0 (centrifuge speed is 10000 r / min, centrifugation is 20 min each time). The washed solid is dried in a drying oven at 60℃ for 24 h to obtain GR / PDDA / PdNPs electrochemical sensing material.

[0037] (5): Take 2 mg of the GR / PDDA / PdNPs electrochemical sensing material obtained in step (4), and ultrasonically disperse it in 2 mL of distilled water to obtain a uniformly dispersed GR / PDDA / PdNPs dispersion with a concentration of 1 mg / mL; perform surface treatment by mechanical polishing on the bare glassy carbon electrode (GCE), and then ultrasonically wash it with anhydrous ethanol and ultrapure water in sequence, and blow it dry with nitrogen. Use a micro sampler to transfer 5 μL of the GR / PDDA / PdNPs dispersion and uniformly drop it onto the surface of the glassy carbon electrode treated above, and let it air dry naturally to obtain the GR / PDDA / PdNPs / GCE electrochemical sensor, i.e., the GR / PDDA / PdNPs / GCE electrode.

[0038] Figure 1 The images show transmission electron microscopy (TEM) images of graphene (a) and the GR / PDDA / PdNPs electrochemical sensing material prepared in Example 1 (b). By comparison, it can be seen that Pd nanoparticles (PdNPs) were successfully loaded onto the GR sheets, indicating that the GR / PDDA / PdNPs electrochemical sensing material has been successfully synthesized.

[0039] Figure 2 These are X-ray diffraction (XRD) patterns of graphene oxide and the GR / PDDA / PdNPs electrochemical sensing material prepared in Example 1. Curve a represents graphene oxide, and curve b represents the GR / PDDA / PdNPs electrochemical sensing material. Figure 2 It can be observed that curve a has a characteristic diffraction peak at 2θ = 10°, which is due to the introduction of oxygen-containing functional groups at the (002) plane. Curve b has a characteristic diffraction peak at 2θ = 25.3°, which corresponds to the diffraction peak of the (002) crystal plane of graphene. In addition, curve b also has obvious diffraction peaks at 2θ of 39.18°, 45.42°, and 66.69°, which belong to the (111), (200), and (220) crystal planes of cubic Pd, respectively. XRD analysis shows that nano-Pd has been firmly loaded onto the graphene substrate.

[0040] (I) Performance testing of GR / PDDA / PdNPs / GCE electrochemical sensors:

[0041] Following the preparation method of Example 1, except that palladium chloride is not added in step (2), the rest are the same as steps (1) to (5) of Example 1, to obtain the GR / PDDA / GCE electrode. Using a saturated calomel electrode as the reference electrode, a platinum wire electrode as the counter electrode, and the bare GCE electrode (hereinafter referred to as the GCE electrode), the GR / PDDA / GCE electrode, and the GR / PDDA / PdNPs / GCE electrode prepared in Example 1 as working electrodes, a three-electrode system is formed. The three-electrode system is placed in a 5.0 × 10⁻⁶ ohmmeter. -4 In a mol / L potassium ferricyanide solution, the potential scan range was set to 0.6~-0.2V, and the scan rate was 0.1V / s. Cyclic voltammetric curves of potassium ferricyanide on GR / PDDA / PdNPs / GCE electrodes (a), (b), and (c) were investigated. The results are as follows: Figure 3 As shown. From Figure 3 It can be seen that the peak current of potassium ferricyanide on the GR / PDDA / PdNPs / GCE electrode is significantly greater than that on the GR / PDDA / GCE electrode and the GCE electrode. The actual surface area of ​​the GR / PDDA / PdNPs / GCE electrode is significantly increased, which improves the charge transfer rate of potassium ferricyanide at the electrode-electrolyte interface.

[0042] AC impedance testing at 5.0 × 10 -4 The experiment was conducted in a K3[Fe(CN)6] / K4[Fe(CN)6] solution containing 0.1 mol / L KCl, with a molar ratio of K3[Fe(CN)6] to K4[Fe(CN)6] of 1:1. A saturated calomel electrode was used as the reference electrode, a platinum wire electrode as the counter electrode, and a GCE electrode, a GR / PDDA / GCE electrode, and the GR / PDDA / PdNPs / GCE electrode prepared in Example 1 as the working electrodes, forming a three-electrode system. The three-electrode system was placed in the aforementioned K3[Fe(CN)6] / K4[Fe(CN)6] solution, and the impedance of the three electrochemical sensors was examined in the frequency range of 0.1–100 kHz and the amplitude of 0.005 V. Figure 4The figures show the AC impedance curves of K3Fe(CN)6 / K4Fe(CN)6 on the GR / PDDA / PdNPs / GCE electrode (a), GR / PDDA / GCE electrode (b), and GCE electrode (c). Using ZSimpWin impedance fitting, the GCE electrode showed the highest impedance value at 360.5 Ω, while the GR / PDDA / PdNPs / GCE electrode showed the lowest at 65.39 Ω. Compared to the GR / PDDA / GCE electrode and the GCE electrode, the GR / PDDA / PdNPs / GCE electrode exhibited a better electrochemical response, improving measurement sensitivity. This may be due to the GR / PDDA / PdNPs electrochemical sensing material prepared in Example 1 accelerating the charge conduction rate.

[0043] (II) Application and condition optimization of GR / PDDA / PdNPs / GCE electrochemical sensor: The three-electrode system in the following application and application condition optimization refers to the three-electrode system consisting of a saturated calomel electrode as the reference electrode, a platinum wire electrode as the counter electrode, and the GR / PDDA / PdNPs / GCE electrode prepared in Example 1 as the working electrode.

[0044] (1) Screening of supporting electrolytes for the electrochemical response of basildipine: The voltammetric response of basildipine was investigated using four supporting electrolytes: acetate-sodium acetate buffer, PBS buffer, BR buffer, and citrate-sodium citrate buffer. Specific experimental conditions were as follows: 2.0 × 10⁻⁶ solutions were prepared in each of the four supporting electrolytes (pH 6.0) to a concentration of 2.0 × 10⁻⁶. -5 A mol / L barnidipine solution was used. The three-electrode system was placed in barnidipine solutions of the four supporting electrolytes mentioned above, respectively. The potential scan range was set to -0.2 to -1.1 V, and the scan rate was 0.1 V / s. Cyclic voltammetry curves of barnidipine in the four supporting electrolytes were recorded. The results are as follows: Figure 5 As shown. From Figure 5 It can be seen that barnidipine exhibits smaller peak currents in citrate-sodium citrate buffer solution (curve a), PBS buffer solution (curve b), and BR buffer solution (curve c), while showing a better peak shape and larger peak current in acetate-sodium acetate buffer solution (curve d). Therefore, acetate-sodium acetate buffer solution was chosen as the supporting electrolyte for the measurement of barnidipine.

[0045] (2) Screening the optimal pH of the supporting electrolyte: Fluctuations in the pH of the supporting electrolyte can affect the electrochemical behavior of the analyte barnidipine. Acetic acid-sodium acetate buffer solutions with different pH values ​​(pH range 2.2–7.2) were used as supporting electrolytes, and solutions with a concentration of 2.0 × 10⁻⁶ were prepared. -5A mol / L barnidipine solution was used. A three-electrode system was placed in barnidipine solutions at different pH values ​​(pH range 2.2–7.2). The potential scan range was set to -0.43 to -1.22 V, and the scan rate was 0.1 V / s. Linear sweep voltammetry curves of barnidipine in acetate-sodium acetate buffer solutions at different pH values ​​were recorded. The results are as follows: Figure 6 As shown. Figure 6 In the diagram, curves a through g represent pH values ​​of: a=2.2, b=2.7, c=3.5, d=4.1, e=5.0, f=6.8, and g=7.2, respectively. From... Figure 6 It can be seen that the reduction peak signal of barnidipine is stronger when the pH of the acetate-sodium acetate buffer solution is 6.8~7.2.

[0046] (3) Enrichment time: Open-circuit enrichment is usually one of the means to improve the sensitivity of trace substance measurement. The three-electrode system is placed in a solution containing 2.0 × 10 -5 Cyclic voltammetry curves of barnidipine were recorded at different enrichment times (30–200 s) in an acetate-sodium acetate buffer solution (pH=6.8) at a potential scan range of -0.43 to -1.22 V and a scan rate of 0.1 V / s. The results showed that the reduction peak signal of barnidipine was stronger at enrichment times of 140–160 s.

[0047] The screening experiments above show that when using a three-electrode system consisting of a GR / PDDA / PdNPs / GCE electrochemical sensor, a saturated calomel electrode, and a platinum wire electrode to detect barnidipine content, the preferred supporting electrolyte is an acetate-sodium acetate buffer solution with a pH of 6.8-7.2, and the preferred enrichment time is 140-160 s.

[0048] (4) Detection limit: Under the above-mentioned preferred measurement conditions, using an acetate-sodium acetate buffer solution with pH=6.8 as the supporting electrolyte, different concentrations of barnidipine solutions were prepared. Linear sweep voltammetric curves of different concentrations of barnidipine solutions were collected using a three-electrode system. The results are as follows: Figure 7 As shown. Figure 7 Curves a to l represent linear sweep voltammetry curves of barnidipine solutions of different concentrations. It can be seen that barnidipine exhibits a sensitive reduction peak at -0.78 V. Figure 8 yes Figure 7 Enlarged view of the inner illustration, by Figure 7 and Figure 8 It can be seen that at 4.0×10 -7 ~2.0×10 -5 Within the mol / L range, the peak current showed a linear relationship with the concentration of barnidipine, and the detection limit was 1.3 × 10⁻⁶. -7 mol / L.

[0049] (5) Selectivity: Under the above-mentioned preferred measurement conditions, the interference of foreign substances on the detection of barnidipine content was investigated using linear sweep voltammetry. Nine parallel aliquots with a concentration of 2.0 × 10⁻⁶ were prepared using an acetate-sodium acetate buffer solution at pH 6.8 as the supporting electrolyte. -5 Eight portions of a mol / L barnidipine solution were each added with the interfering substance Mg. 2+ Al 3+ Cl - Glucose, sucrose, ascorbic acid, caffeine, and nimesulide were used as the interference group. After the interference substances were added, Mg... 2+ Al 3+ Cl - The concentrations were all 2.0 × 10⁻⁶. -3 The concentrations of glucose, sucrose, ascorbic acid, caffeine, and nimesulide were all 2.0 × 10 mol / L. -5 mol / L. The remaining portion is 2.0 × 10⁻⁶ mol / L. -5 A mol / L barnidipine solution without interfering substances was used as a blank control group. The three-electrode system was placed in the solutions of the interference group and the blank control group, respectively. The enrichment time was set to 150 s, the potential scan range was -0.43 to -1.22 V, and the scan rate was 0.1 V / s. The linear scan voltammetric curve of barnidipine was recorded, and the peak current change value was calculated. The peak current change value = [(peak current of interference group - peak current of blank group) / peak current of blank group] × 100%. The results are shown in Table 1.

[0050] Table 1. Changes in peak current of Banidi after adding different interfering substances

[0051]

[0052] As shown in Table 1, the peak current variation of barnidipine was less than ±5% in the presence of interfering substances, indicating that the GR / PDDA / PdNPs / GCE electrochemical sensor has high selectivity for measuring barnidipine content under the preferred measurement conditions.

[0053] (6) Reproducibility: Under the preferred measurement conditions described above, the reproducibility of the GR / PDDA / PdNPs / GCE electrochemical sensor in measuring barnidipine content was examined using linear sweep voltammetry. Six aliquots with a concentration of 2.0 × 10⁻⁶ were prepared using an acetate-sodium acetate buffer solution at pH 6.8 as the supporting electrolyte. -5 A 2.0 × 10⁻⁶ mol / L barnidipine solution was used. A three-electrode system was placed in six separate portions of barnidipine solution. The potential scan range was set to -0.43 to -1.22 V, the scan rate to 0.1 V / s, and the enrichment time to 150 s. The enrichment time was 150 s for each of the six 2.0 × 10⁻⁶ mol / L barnidipine solutions. -5Parallel tests were performed using mol / L barnidipine solution to measure the peak current fluctuations of barnidipine in six solutions on the GR / PDDA / PdNPs / GCE electrochemical sensor. The results are shown in Table 2. Table 2 shows that the reproducibility RSD of the six parallel tests was 2.78%, indicating that the GR / PDDA / PdNPs / GCE electrochemical sensor prepared in this embodiment has high reproducibility for barnidipine measurement.

[0054] Table 2. 6 portions of 2.0 × 10 -5 Parallel test results of mol / L barnidipine solution

[0055]

[0056] (7) Stability: An acetate-sodium acetate buffer solution with pH=6.8 was used as the supporting electrolyte to prepare a solution with a concentration of 2.0×10⁻⁶. -5 A mol / L barnidipine solution was used to prepare the three-electrode system. The potential scan range was set to -0.43 to -1.22 V, the scan rate was 0.1 V / s, and the enrichment time was 150 s. The peak current signal of barnidipine was initially measured and recorded. After the initial barnidipine measurement, the GR / PDDA / PdNPs / GCE electrochemical sensor was stored at room temperature for one week. Then, the peak current signal of the same barnidipine solution was measured and recorded again. The comparison of the two measurements showed that the peak current signal value of the second measurement was reduced by 4.25% compared with the initial measurement, indicating that the prepared GR / PDDA / PdNPs / GCE electrochemical sensor has good stability.

[0057] (8) Recovery rate: Under the above-mentioned preferred measurement conditions, using an acetate-sodium acetate buffer solution with pH=6.8 as the supporting electrolyte, two groups of barnidipine sample solutions were prepared, with three parallel preparations for each group. Each sample solution was scanned using the aforementioned three-electrode system via linear scanning voltammetry. The potential scan range was set to -0.43 to -1.22 V, the scan rate to 0.1 V / s, and the enrichment time to 150 s. The obtained peak current was then used to... Figure 8 The corresponding barnidipine concentration was calculated from the standard curve equation. The concentrations of the first group of barnidipine sample solutions were 1.05 × 10⁻⁶. -5 mol / L, 1.12×10 -5 mol / L, 1.08×10 -5 The concentration of barnidipine in the second group of samples was 2.43 × 10 mol / L. -5 mol / L, 2.35×10 -5 mol / L, 2.38×10 -5mol / L. A spiked recovery experiment was also conducted, and the recovery rate and RSD were calculated. The results are shown in Table 3.

[0058] Table 3. Results of Sample Solution and Spike Recovery Experiment

[0059]

[0060] As shown in Table 3, the spiked recovery rate was 95.63%~102.38%, which indicates that the GR / PDDA / PdNPs / GCE electrochemical sensor prepared in this embodiment has high accuracy in determining the content of barnidipine and can be used to determine the content of barnidipine in actual samples.

[0061] The above experiments show that when the GR / PDDA / PdNPs / GCE electrochemical sensor is used to determine the content of barnidipine, an acetate-sodium acetate buffer solution with a pH of 6.8-7.2 is preferred as the supporting electrolyte, and the open-circuit enrichment time is preferably 140-160 s. -7 ~2.0×10 -5 Within the concentration range of mol / L, the peak current showed a linear relationship with the concentration of barnidipine, and the limit of detection was 1.3 × 10⁻⁶. -7 mol / L.

[0062] Example 2

[0063] (1): Weigh 100 mg of graphene oxide and place it in 100 mL of distilled water and ultrasonically disperse it for 2.5 h to prepare a 1 mg / mL graphene oxide suspension;

[0064] (2): 3 mL of PDDA with a mass fraction of 35% was slowly added to the graphene oxide suspension obtained in step (1), stirred for 1.5 h, and then 10 mg of palladium chloride was added to it and stirred for another 1 h to obtain a mixture.

[0065] (3): Add 4 mL of 1 mg / mL NaBH4 solution dropwise to the mixture obtained in step (2), stir until homogeneous, heat the mixture to 50°C, stir at this temperature for 6 h, and then cool naturally to room temperature;

[0066] (4): The product cooled in step (3) is centrifuged and separated. The separated solid is washed with distilled water 3 to 5 times until the pH of the supernatant after washing is 7.0 (centrifuge speed is 10000 r / min, centrifugation time is 25 min each time). The washed solid is dried in a drying oven at 60℃ for 24 h to obtain GR / PDDA / PdNPs electrochemical sensing material.

[0067] (5): Take 3 mg of the GR / PDDA / PdNPs electrochemical sensing material obtained in step (4), and ultrasonically disperse it in 3 mL of distilled water to obtain a uniformly dispersed GR / PDDA / PdNPs dispersion with a concentration of 1 mg / mL; perform surface treatment by mechanical polishing on the bare glassy carbon electrode, and then ultrasonically wash it with anhydrous ethanol and ultrapure water in sequence, and blow it dry with nitrogen; use a micro sampler to transfer 6 μL of the GR / PDDA / PdNPs dispersion and uniformly drop it onto the surface of the glassy carbon electrode treated above, and let it air dry naturally to obtain the GR / PDDA / PdNPs / GCE electrochemical sensor.

[0068] Using the GR / PDDA / PdNPs / GCE electrochemical sensor prepared in this embodiment as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum wire electrode as the counter electrode, a three-electrode system was formed. An acetate-sodium acetate buffer solution with pH=7.0 was selected as the supporting electrolyte for measurement. Barnidipine solutions of different concentrations were prepared, and open-circuit enrichment was performed for 150 s. The response peak current of the GR / PDDA / PdNPs / GCE electrochemical sensor prepared in this embodiment at different concentrations was recorded. The results show that at 4.8 × 10⁻⁶... -7 ~2.0×10 -5 Within the mol / L range, the peak current showed a linear relationship with the concentration of barnidipine, and the detection limit was 1.4 × 10⁻⁶. -7 mol / L. The spiked recovery experiment was conducted using the same method as in Example 1, and the recovery rate was 97.46–102.35%, indicating that the GR / PDDA / PdNPs / GCE electrochemical sensor prepared in this example has high accuracy in determining the content of barnidipine and can be used for the determination of barnidipine in actual samples.

[0069] Example 3

[0070] (1): Weigh 110 mg of graphene oxide and place it in 110 mL of distilled water and ultrasonically disperse for 3 h to prepare a 1 mg / mL graphene oxide suspension;

[0071] (2): 4 mL of 35% PDDA was slowly added to the graphene oxide suspension obtained in step (1), stirred for 2 h, and then 12 mg of palladium chloride was added and stirred for another 1 h to obtain a mixture.

[0072] (3): Add 5 mL of NaBH4 solution with a concentration of 1 mg / mL dropwise to the mixture obtained in step (2), stir evenly, heat the mixture to 60°C, stir at this temperature for 7 h, and then cool naturally to room temperature;

[0073] (4): The product cooled in step (3) is centrifuged and separated. The separated solid is washed with distilled water 3 to 5 times until the pH of the supernatant after washing is 7.0 (centrifuge speed is 10000 r / min, centrifugation is 30 min each time). The washed solid is dried in a drying oven at 70 ℃ for 20 h to obtain GR / PDDA / PdNPs electrochemical sensing material.

[0074] (5): Take 4 mg of the GR / PDDA / PdNPs electrochemical sensing material obtained in step (4), and ultrasonically disperse it in 4 mL of distilled water to obtain a uniformly dispersed GR / PDDA / PdNPs dispersion with a concentration of 1 mg / mL; perform surface treatment by mechanical polishing on the bare glassy carbon electrode, and then ultrasonically wash it with anhydrous ethanol and ultrapure water in sequence, and blow it dry with nitrogen; use a micro sampler to transfer 7 μL of the GR / PDDA / PdNPs dispersion and uniformly drop it onto the surface of the glassy carbon electrode treated above, and let it air dry naturally to obtain the GR / PDDA / PdNPs / GCE electrochemical sensor.

[0075] Using the GR / PDDA / PdNPs / GCE electrochemical sensor prepared in this embodiment as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum wire electrode as the counter electrode, a three-electrode system was formed. An acetate-sodium acetate buffer solution with pH=7.2 was selected as the supporting electrolyte for measurement. Barnidipine solutions of different concentrations were prepared, and open-circuit enrichment was performed for 160 s. The response peak current of the GR / PDDA / PdNPs / GCE electrochemical sensor prepared in this embodiment at different concentrations was recorded. The results show that at 4.2 × 10⁻⁶... -7 ~1.8×10 -5 Within the mol / L range, the peak current showed a linear relationship with the concentration of barnidipine, and the detection limit was 1.5 × 10⁻⁶. -7 mol / L. Spiking recovery experiments were conducted using the same method as in Example 1, and the recovery rate was 96.43–101.28%, indicating that the GR / PDDA / PdNPs / GCE electrochemical sensor prepared in this example has high accuracy in determining the content of barnidipine and can be used for the determination of barnidipine in actual samples.

[0076] The graphene oxide in the above embodiments was prepared from graphite powder using the modified Hummers method. This technology is a mature existing technology and will not be described in detail here.

[0077] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. The application of the GR / PDDA / PdNPs / GCE electrochemical sensor in the detection of barnidipine content, characterized in that, Using a GR / PDDA / PdNPs / GCE electrochemical sensor as the working electrode, a platinum wire electrode as the counter electrode, and a saturated calomel electrode as the reference electrode, linear sweep voltammetry was employed. An acetate-sodium acetate buffer solution with a pH of 6.80–7.20 was used as the supporting electrolyte. The enrichment time was 140–160 s, and the barnidipine concentration was 4.0 × 10⁻⁶. -7 ~2.0×10 -5 Within the mol / L range, the peak current showed a linear relationship with the concentration, and the detection limit was 1.3 × 10⁻⁶. -7 mol / L; the preparation method of the GR / PDDA / PdNPs / GCE electrochemical sensor includes: (1) Graphene oxide was ultrasonically dispersed in distilled water to prepare a 1 mg / mL graphene oxide suspension; (2) A certain amount of PDDA is slowly added to the graphene oxide suspension obtained in step (1), and stirred for 1-2 h. Then palladium chloride is added to it, and stirring is continued for 1-2 h to obtain a mixture. The mass fraction of PDDA is 35%, and the volume ratio of its added volume to the volume of the graphene oxide suspension is 1:(25-50). (3) Add NaBH4 solution dropwise to the mixture obtained in step (2), stir until homogeneous, heat the mixture to 40~60℃, stir at this temperature for 5~7 h, and then let it cool naturally to room temperature. (4) Centrifuge the product cooled in step (3), wash the separated solid with distilled water until the pH of the supernatant after washing is 7.0, and dry the washed solid in a drying oven at 60~70℃ for 20~24 h to obtain GR / PDDA / PdNPs electrochemical sensing material. (5) The GR / PDDA / PdNPs electrochemical sensing material is ultrasonically dispersed in distilled water to obtain a GR / PDDA / PdNPs dispersion. 5~7 μL of the GR / PDDA / PdNPs dispersion is evenly dropped onto the surface of the treated glassy carbon electrode and allowed to air dry to obtain the GR / PDDA / PdNPs / GCE electrochemical sensor.

2. The application of the GR / PDDA / PdNPs / GCE electrochemical sensor as described in claim 1 in the detection of barnidipine content, characterized in that, The ratio of the mass of palladium chloride added to the mass of graphene oxide in step (1) is 1:(9~10).

3. The application of the GR / PDDA / PdNPs / GCE electrochemical sensor as described in claim 1 in the detection of barnidipine content, characterized in that, The concentration of the NaBH4 solution is 1 mg / mL, and the volume ratio of its added volume to the volume of the graphene oxide suspension obtained in step (1) is 1:(20~30).

4. The application of the GR / PDDA / PdNPs / GCE electrochemical sensor as described in claim 1 in the detection of barnidipine content, characterized in that, In step (5), the concentration of the GR / PDDA / PdNPs dispersion is 1 mg / mL.

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