3D-rGO / Au / beta-CD modified electrode and preparation method and application thereof

Abstract

The invention provides a 3D-rGO / Au / beta-CD modified electrode as well as a preparation method and application of the 3D-rGO / Au / beta-CD modified electrode. The preparation of the modified electrode comprises the following steps: preparing 3D-rGO through an oil bath method, and further depositing 3D-rGO, Au and beta-CD on the surface of a glassy carbon electrode (GCE) through a dispensing method and an electrochemical deposition method, thereby preparing a novel electrochemical sensor and realizing electrochemical sensing of niclosamide (NA). The invention provides a simple and rapid niclosamide detection method based on excellent electrochemical performance of 3D-rGO / Au / beta-CD (three-dimensional rGO / Au / beta-CD). The invention solves the problems of poor material stability, weak selective recognition, high detection limit and narrow detection range in the existing niclosamide detection.

Description

Technical Field

[0001] The invention relates to a modified electrode, in particular to a 3D-rGO / Au / β-CD modified electrode and a preparation method thereof, and application of the modified electrode in electrochemical detection of niclosamide. Background Art

[0002] Since niclosamide (NA) was included in the World Health Organization's list of essential medicines in 1982, it has been widely promoted and used worldwide. However, with the widespread use of niclosamide, its hazards have gradually begun to emerge. Studies have confirmed that niclosamide can cause harm to aquatic organisms and has residues in common foods such as crops, livestock and poultry. Therefore, the development of a highly sensitive and selective analytical method to detect niclosamide is of great significance for the protection of the ecological environment and human health.

[0003] The analytical methods for niclosamide that have been reported so far include "potentiometric titration", "spectrophotometer" and "high performance liquid chromatography". These methods are only applicable to the purity detection of niclosamide technical, and have weak selective recognition of the detected object, high detection limit and narrow detection range.

[0004] The modified 3D graphene nanocomposite has both its inherent properties and the special properties of the modified material, and shows great development potential in sensors and other aspects. In addition, the cavity of the β-CD molecule enables it to selectively bind to molecules of a specific size to form a stable inclusion complex. Functionalizing 3D graphene with β-CD not only improves the hydrophobicity and water dispersion stability of 3D graphene, but also brings into play the host-guest recognition characteristics of β-CD. The present invention combines the advantages of 3D-rGO and β-CD to prepare a 3D-rGO / Au / β-CD modified electrode, the material of which has excellent stability, and can bring into play the host-guest recognition characteristics of β-CD, enhance the selective recognition of niclosamide by the modified electrode, and has a wide detection range and a low detection limit for the detection of niclosamide. Summary of the invention

[0005] The object of the present invention is to provide a 3D-rGO / Au / β-CD modified electrode and a preparation method thereof, and to use the modified electrode for electrochemical detection of niclosamide, so as to solve the problems of poor material stability, weak selective recognition, high detection limit and narrow detection range existing in the existing niclosamide detection.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for preparing a 3D-rGO / Au / β-CD modified electrode comprises the following steps:

[0008] 1) Preparation of 3D-rGO:

[0009] 30-50 mg (preferably 40 mg) of graphene oxide (GO) is ultrasonically treated in 10-30 mL (preferably 20 mL) of deionized water for 3-5 h (preferably 4 h); 30-50 mg (preferably 40 mg) of L-cysteine ​​(L-Cys) is added to the dispersion and 150-250 μL (preferably 200 μL) of ammonia water is added dropwise, stirred until the system is uniform, heated in an oil bath for 2-4 h (preferably 3 h), washed with water twice to remove excess ammonia water, and freeze-dried overnight to obtain 3D-rGO.

[0010] 2) Preparation of 3D-rGO / Au / β-CD modified electrode:

[0011] 5-10 mg (preferably 10 mg) of 3D-rGO was ultrasonically treated in 5-10 mL (preferably 10 mL) of deionized water for 30-60 min (preferably 60 min) to obtain a 3D-rGO suspension; 5-10 μL (preferably 5 μL) of the 3D-rGO suspension was drop-coated on the surface of a glassy carbon electrode (GCE) and dried to obtain a 3D-rGO modified electrode; the 3D-rGO modified electrode was first immersed in 1 mM HAuCl 4 The 3D-rGO / Au modified electrode was immersed in 1 mM β-CD solution and subjected to cyclic voltammetry (CV) scanning. The electrode was rinsed with water and then dried to obtain a 3D-rGO / Au modified electrode. The 3D-rGO / Au modified electrode was immersed in 1 mM β-CD solution and subjected to cyclic voltammetry (CV) scanning. The electrode was rinsed with deionized water and then dried to obtain a 3D-rGO / Au / β-CD modified electrode.

[0012] A method for electrochemically detecting niclosamide (NA) using a 3D-rGO / Au / β-CD modified electrode comprises the following steps:

[0013] 1) Electrochemical characterization of 3D-rGO / Au / β-CD modified electrode:

[0014] The 3D-rGO / Au / β-CD modified electrode was immersed in a solution containing 0.1M KCl, 5mM [Fe(CN) 6 ] 3- / 4- In the mixed solution, the cyclic voltammetry (CV) characterization showed a higher peak current value;

[0015] 2) Electrochemical detection of niclosamide:

[0016] The 3D-rGO / Au / β-CD modified electrode was immersed in a PBS buffer solution with pH = 8.0 containing 10 μM niclosamide, and a differential pulse voltammetry (DPV) test was performed. The experiment proved that the 3D-rGO / Au / β-CD modified electrode was capable of electrochemical detection of niclosamide and showed high selectivity.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention prepares a 3D-rGO / Au / β-CD modified electrode. The modified 3D graphene nanocomposite has both its inherent properties and the special properties of the modified material; the excellent electrocatalytic performance and biocompatibility of AuNPs can enhance the overall stability of the nanomaterial complex; the cavity of the β-CD molecule enables it to selectively combine with molecules of a specific size to form a stable inclusion complex.

[0019] (2) The functionalization of 3D graphene with β-CD not only improves the hydrophobicity and water dispersion stability of 3D graphene, but also exerts the host-guest recognition properties of β-CD to enhance the selectivity of the composite material.

[0020] (3) The novel electrochemical sensor for niclosamide detection constructed in the present invention synergistically exerts the excellent electrochemical properties of 3D-rGO and the molecular recognition characteristics of β-CD. Under optimized conditions, the detection of niclosamide achieves a wider detection range and a lower detection limit.

[0021] (4) The present invention studies the electrochemical behavior of niclosamide on the surface of the modified electrode by the DPV method, and provides an electrochemical method for detecting niclosamide using 3D-rGO / Au / β-CD, which plays an indispensable role in the research of electrochemical sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 SEM images: (A) AuNPs, (B) 3D-rGO / Au, (C) 3D-rGO / Au / β-CD.

[0023] Figure 2 It is an infrared spectrum.

[0024] Figure 3 XPS graphs: (A) full spectrum; (B) 3D-rGO C1s spectrum, (C) 3D-rGO / Au C1s spectrum; (D) 3D-rGO / Au / β-CD C1s spectrum; (E) 3D-rGO / Au Au4f spectrum.

[0025] Figure 4 For bare GCE, 3D-rGO / GCE, 3D-rGO / Au / GCE, and 3D-rGO / Au / β-CD / GCE in 5 mM [Fe(CN) 6 ] 3- / 4- Cyclic voltammogram in solution (A) and differential pulse voltammogram in niclosamide solution (B).

[0026] Figure 5Cyclic voltammograms at different scan rates (A); linear relationship between peak current and scan rate (B); linear relationship between peak potential and the logarithm of scan rate (C).

[0027] Figure 6 It is a line graph at different pH (A), enrichment time (B), and modification volume (C).

[0028] Figure 7 DPV diagram (A) and linear diagram (B) of different concentrations of niclosamide.

[0029] Figure 8 Figure 2 shows the selectivity of 3D-rGO / Au / β-CD / GCE sensor pair for niclosamide in the presence of interferents.

[0030] Fig. 9 The H NMR spectra of β-CD, NA and β-CD+NA inclusion complex (A) and the two-dimensional ROSEY H NMR spectrum of the mixture of NA and β-CD (B). DETAILED DESCRIPTION

[0031] The present invention is further described in detail below with reference to the examples, but the examples do not limit the protection scope of the present invention.

[0032] Embodiment 1:

[0033] The preparation method of 3D-rGO / Au / β-CD modified electrode comprises the following steps:

[0034] 1) Preparation of 3D-rGO:

[0035] 40 mg of graphene oxide (GO) was ultrasonically treated in 20 mL of deionized water for 4 h; 40 mg of L-cysteine ​​(L-Cys) was added to the dispersion and 200 μL of ammonia water was added dropwise. After stirring until the system was uniform, it was heated in an oil bath for 3 h, and the excess ammonia water was washed twice with water, and freeze-dried overnight to obtain 3D-rGO.

[0036] 2) Preparation of 3D-rGO / Au / β-CD modified electrode:

[0037] 10 mg 3D-rGO was ultrasonically treated in 10 mL deionized water for 60 min to obtain a 3D-rGO suspension. 5 μL of the 3D-rGO suspension was drop-coated on the surface of a glassy carbon electrode (GCE) and dried to obtain a 3D-rGO modified electrode. The 3D-rGO modified electrode was first immersed in 1 mM HAuCl 4The 3D-rGO / Au modified electrode was immersed in 1 mM β-CD solution and subjected to cyclic voltammetry (CV) scanning. The electrode was rinsed with water and then dried to obtain a 3D-rGO / Au modified electrode. The 3D-rGO / Au modified electrode was immersed in 1 mM β-CD solution and subjected to cyclic voltammetry (CV) scanning. The electrode was rinsed with deionized water and then dried to obtain a 3D-rGO / Au / β-CD modified electrode.

[0038] The method for electrochemically detecting niclosamide (NA) using a 3D-rGO / Au / β-CD modified electrode comprises the following steps:

[0039] 1) Electrochemical characterization of 3D-rGO / Au / β-CD modified electrode:

[0040] The 3D-rGO / Au / β-CD modified electrode was immersed in a solution containing 0.1M KCl, 5mM [Fe(CN) 6 ] 3- / 4- In the mixed solution, the cyclic voltammetry (CV) characterization showed a higher peak current value;

[0041] 2) Electrochemical detection of niclosamide:

[0042] The 3D-rGO / Au / β-CD modified electrode was immersed in a PBS buffer solution with pH = 8.0 containing 10 μM niclosamide, and a differential pulse voltammetry (DPV) test was performed. The experiment proved that the 3D-rGO / Au / β-CD modified electrode was capable of electrochemical detection of niclosamide and showed high selectivity.

[0043] Embodiment 2:

[0044] The preparation method of 3D-rGO / Au / β-CD modified electrode comprises the following steps:

[0045] 1) Preparation of 3D-rGO:

[0046] 30 mg of graphene oxide (GO) was ultrasonically treated in 10 mL of deionized water for 3 h; 30 mg of L-cysteine ​​(L-Cys) was added to the dispersion and 150 μL of ammonia water was added dropwise, stirred until the system was uniform, and then heated in an oil bath for 2 h. The excess ammonia water was washed twice with water and freeze-dried overnight to obtain 3D-rGO.

[0047] 2) Preparation of 3D-rGO / Au / β-CD modified electrode:

[0048] 5 mg 3D-rGO was ultrasonically treated in 5 mL deionized water for 30 min (, to obtain a 3D-rGO suspension; 10 μL of the 3D-rGO suspension was drop-coated on the surface of a glassy carbon electrode (GCE) and dried to obtain a 3D-rGO modified electrode; the 3D-rGO modified electrode was first immersed in 1 mM HAuCl 4The 3D-rGO / Au modified electrode was immersed in 1 mM β-CD solution and subjected to cyclic voltammetry (CV) scanning. The electrode was rinsed with water and then dried to obtain a 3D-rGO / Au modified electrode. The 3D-rGO / Au modified electrode was immersed in 1 mM β-CD solution and subjected to cyclic voltammetry (CV) scanning. The electrode was rinsed with deionized water and then dried to obtain a 3D-rGO / Au / β-CD modified electrode.

[0049] The method for electrochemical detection of niclosamide (NA) using 3D-rGO / Au / β-CD modified electrode is the same as that in Example 1.

[0050] The modified electrode prepared in Example 1 was used for characterization and analysis below:

[0051] Figure 1 This is the SEM picture. Figure 1 The AuNPs in A have a spherical structure with uniform particle size; in 1B and 1C, similar spherical structures can be observed, with uniform distribution and no aggregation, proving that AuNPs are successfully loaded on the 3D-rGO surface; at the same time, 3D-rGO / Au has a typical structure of obvious three-dimensional graphene; Figure C shows that the overall morphology of the material has not changed, proving that the modification of β-CD has not affected the main structure of the material.

[0052] Figure 2 is an infrared spectrum. Figure 2 Compared with 3D-rGO, the 3D-rGO / Au spectrum did not change significantly. After modification with Au, the main structure of 3D-rGO was not destroyed. In the infrared spectrum, the -1 With 2928cm -1 The peak at 2928cm in the spectrum of 3D-rGO / Au / β-CD is the -OH and -CH vibration absorption peak of cyclodextrin; -1 , 1642cm -1 , 1163cm -1 The characteristic peak of β-CD appeared at 1709 cm -1 The new peak at is the ester bond formed by esterification of the carboxyl groups on the 3D-rGO surface with the hydroxyl groups of β-CD, indicating that β-CD is successfully modified on the 3D-rGO / Au surface.

[0053] Figure 3 is the XPS spectrum. Figure 3As shown in A, 3D-rGO, 3D-rGO / Au, and 3D-rGO / Au / β-CD all contain C, N, and O elements, and the presence of Au elements in 3D-rGO / Au and 3D-rGO / Au / β-CD indicates that they are successfully modified on the surface of 3D-rGO; the ratio of C, N, and O elements between 3D-rGO and 3D-rGO / Au is basically unchanged, indicating that the loading of Au does not destroy the main structure of 3D-rGO; the increase in the bond energy of C and O in 3D-rGO / Au / β-CD indicates that cyclodextrin has been successfully loaded on the surface of 3D-rGO / Au. Figure 3 B, 3C, and 3D are the C1s spectra of 3D-rGO, 3D-rGO / Au, and 3D-rGO / Au / β-CD, respectively. The contents of CO-related peaks in 3D-rGO / Au / β-CD: CO (286.2 eV), C=O (287.4 eV), and OC=O (288.7 eV) are significantly increased compared with the contents of CO-related peaks in 3D-rGO / Au, indicating the successful modification of β-CD. Figure 3 Au4f in E 5 / 2 (87.67 eV) and Au4f 7 / 2 (84.00 eV) confirmed the successful preparation of 3D-rGO / Au / β-CD composites.

[0054] Figure 4 Cyclic voltammograms (CV) and differential pulse voltammograms (DPV) of different modified electrodes in corresponding solutions. Figure 4 The peak currents of the four electrodes shown in A are 3D-rGO / Au / β-CD / GCE>3D-rGO / Au / GCE>3D-rGO / GCE>bare GCE; the modification of Au enhances the conductivity, and the modification of β-CD enhances the dispersion and improves the conductivity of the composite material. Figure 4 B, 3D-rGO / GCE itself has no electrochemical response to NA, but after being modified with AuNPs, it responds to niclosamide due to the electrocatalytic effect of metal nanoparticles. The electrochemical response of 3D-rGO / β-CD / GCE to niclosamide is attributed to the recognition of niclosamide by β-CD.

[0055] Figure 5 CV graphs of 3D-rGO / Au / β-CD / GCE for niclosamide at different scanning rates. Figure 5 The CV curve in A shows only a weak oxidation peak, indicating that its reaction on the electrode surface is irreversible. Figure 5 The peak current in B showed a good linear correlation with the scan rate within 40 to 240 mV / s: Ip = 0.07740ν + 1.710 (R 2 =0.9972), indicating that the electron transfer of niclosamide on the electrode is a typical diffusion-controlled process; Figure 5 The linear equation of the oxidation peak potential and the logarithm of the scan rate of niclosamide in C is: E = -0.05545logν-0.1242(R 2 =0.9978)

[0056] Figure 6 The results under different pH, enrichment time and modification volume show that pH=8 is the optimal pH value (6A), 90 seconds is the optimal enrichment time (6B), and 5 μL is the optimal modification volume (6C).

[0057] Figure 7 This is the DPV response diagram of rGO / Au / β-CD / GCE to different concentrations of niclosamide under the optimal experimental conditions. Figure 7 The peak current of niclosamide in A increases with the increase of concentration, and the i value shows a strong concentration dependence, showing two different linear relationships in the concentration range of 0.02μM-200μM ( Figure 7 B), the linear equation in the concentration range of 0.02 to 4 μM is: p (μA)=6.919+2.172logc(μM)(R 2 =0.9731); the linear equation in the concentration range of 4 to 200 μM is: p (μA)=-6.652+27.40logc(μM)(R 2 =0.9878); detection limit was 6.667 nM.

[0058] Figure 8 The interference determination of 3D-rGO / Au / β-CD composite material for the detection of niclosamide. Figure 8 After adding the interferents, the current response was not significantly disturbed, indicating that the prepared 3D-rGO / Au / β-CD / GCE has good anti-interference ability.

[0059] Fig. 9 These are the one-dimensional H-NMR spectra of NA, β-CD, and NA+β-CD, and the two-dimensional ROSEY H-NMR spectrum of NA+β-CD. Fig. 9 As shown in A and Tables 1 and 2, the protons on the benzene ring of NA moved to the downfield, indicating that host-guest interaction occurred between β-CD and NA; the H 1 , H 3 , H 5 , H 6 The chemical shift of NA has shifted significantly, that is, NA enters the cavity of β-CD and the two form an inclusion complex. Fig. 9 B, H in the cyclodextrin cavity 3The hydrogen atoms Ha~Hg on the benzene ring of NA all produce correlation peaks. Combined with 1H-NMR, it shows that the benzene ring structure of NA can enter the cyclodextrin cavity and form an effective inclusion complex through host-guest interaction.

[0060] Table 1 1H chemical shift of NA in the presence and absence of β-CD

[0061]

[0062] Table 2 1H chemical shifts in the presence and absence of NA

[0063]

[0064] The embodiments described above are only descriptions of preferred implementations of the present invention and do not limit the concept and protection scope of the present invention. Without departing from the design concept of the present invention, ordinary technicians in this field can make various modifications and changes to the technical solution of the present invention, which should all fall within the protection scope of the present invention.

Claims

1. Application of a 3D-rGO / Au / β-CD modified electrode in electrochemical detection of niclosamide, wherein the modified electrode is prepared by a method comprising the following steps: 1) Preparation of 3D-rGO: 30-50 mg of graphene oxide (GO) was ultrasonically treated in 10-30 mL of deionized water for 3-5 h; 30-50 mg of L-cysteine ​​(L-Cys) was added to the dispersion and 150-250 μL of ammonia water was added dropwise, stirred until the system was uniform, and then heated in an oil bath for 2-4 h, and the excess ammonia water was washed off twice with water, and freeze-dried overnight to obtain 3D-rGO; 2) Preparation of 3D-rGO / Au / β-CD modified electrode: 5-10 mg 3D-rGO was ultrasonically treated in 5-10 mL deionized water for 30-60 min to obtain a 3D-rGO suspension; 5-10 μL of the 3D-rGO suspension was drop-coated on the surface of a glassy carbon electrode (GCE) and dried to obtain a 3D-rGO modified electrode; the 3D-rGO modified electrode was immersed in a 1 mM HAuCl4 solution for cyclic voltammetry (CV) scanning, rinsed with deionized water and then baked to obtain a 3D-rGO / Au modified electrode; the 3D-rGO / Au modified electrode was immersed in a 1 mM β-CD solution for cyclic voltammetry (CV) scanning, rinsed with deionized water and then baked to obtain a 3D-rGO / Au / β-CD modified electrode.

2. The use according to claim 1, characterized in that In the step 1), the ultrasonic treatment is performed in deionized water for 4 hours.

3. The use according to claim 1, characterized in that The mass concentration of the ammonia water in step 1) is 25%.

4. The use according to claim 1, characterized in that In step 1), the mixture was heated in an oil bath for 3 h.

5. The use according to claim 1, characterized in that In the step 2), the ultrasonic treatment is performed in deionized water for 60 minutes.

6. The use according to claim 1, characterized in that The voltage scanned in step 2) is -1.6-0.8V.

7. A method for electrochemical detection of niclosamide using a 3D-rGO / Au / β-CD modified electrode, characterized in that: The following steps are involved: 1) Electrochemical characterization of 3D-rGO / Au / β-CD modified electrode: The 3D-rGO / Au / β-CD modified electrode described in claim 1 is immersed in a solution containing 0.1M KCl, 5mM [Fe(CN)6] 3- / 4- Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were performed in a mixed solution, and the 3D-rGO / Au / β-CD modified electrode showed a low electrochemical impedance value and a high peak current value; 2) Electrochemical detection of niclosamide: The 3D-rGO / Au / β-CD modified electrode was immersed in a PBS buffer solution (pH = 8.0) containing 10 μM niclosamide, and differential pulse voltammetry (DPV) test was performed.

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