An electrochemiluminescence sensor based on CS@Cd nanomaterials and its application in catechol detection

Abstract

The present invention relates to the field of chemical sensors, and more particularly to an electrochemiluminescence (ECL) sensor based on CS@Cd nanomaterials and its application in catechol (CA) detection. The electrochemiluminescence sensor is a composite material based on carbon spheres (CS), and a carbon sphere-cadmium composite nanomaterial (CS@Cd) is prepared. After the material is fixed to an electrode, it has a sensitizing effect on the ECL of luminol, thereby improving the sensitivity of CA detection, and can realize the detection of picomolar concentration of CA, and its detection limit (S / N=3) is 2.5×10 ‑12 mol·L ‑1 The catechol detection method of the present invention is simple and convenient to operate.

Description

Technical Field

[0001] The present invention relates to the field of chemical sensors, and in particular to an electrochemiluminescence sensor based on CS@Cd nanomaterials and its application in catechol detection. Background Art

[0002] Catechol (CA) is widely found in vegetables, tea, fruit and tobacco plants. At the same time, as a typical phenolic compound, it is an important intermediate or raw material in the fields of medicine, food, coatings, resins and flavors. However, CA is resistant to degradation and cytotoxic, and has posed a serious threat to the ecological environment and human health. Therefore, it is particularly important to develop highly sensitive and accurate detection methods. Existing methods for detecting CA include electrochemical detection, fluorescence analysis, high performance liquid chromatography (HPLC), gas chromatography, surface plasmon resonance, etc. However, most of these methods have certain limitations, often requiring expensive equipment, complex pretreatment, large background interference, and less than ideal detection limits and sensitivity.

[0003] Electrochemiluminescence (ECL) is a chemiluminescent process triggered by electrochemical technology. ECL detection has the advantages of high sensitivity, good selectivity, low cost, strong controllability, simple operation, and no need for pretreatment. It has gradually developed into a method with application potential in analytical chemistry. In particular, the luminol-H2O2 ECL system has high ECL luminescence efficiency and is easy to prepare into ECL sensors. It has been widely used in the fields of drug analysis, immunoassay, environmental analysis, and clinical diagnosis. Summary of the invention

[0004] To solve the above problems, the present invention provides an electrochemiluminescence sensor based on CS@Cd nanomaterials and its application in catechol detection. After the prepared carbon ball-cadmium composite nanomaterial (CS@Cd) is fixed on the electrode, it has a sensitizing effect on the ECL of luminol, thereby improving the sensitivity of CA detection and realizing the detection of picomolar concentration of CA.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] An electrochemiluminescent sensor based on CS@Cd nanomaterial is prepared by the following steps:

[0007] S1. Take 0.6486g glucose and 0.1108g nicotinic acid, dissolve them in 18mL ultrapure water, transfer the resulting transparent solution to a 25mL reactor, perform hydrothermal reaction at 200℃ for 16h, cool to room temperature, collect the suspended and precipitated brown powder by centrifugation, wash them alternately with ultrapure water and ethanol for several times, and dry them in an oven at 70℃ for 24h to form CS powder;

[0008] S2. Dissolve 0.2284 g of cadmium chloride in 20 mL of ultrapure water, add 0.02 g of CS powder, and perform ultrasonic treatment for 30 min. After stirring for 10 min, slowly add 0.1402 g of hexamethylenetetramine. Continue stirring for 5 h, alternately use ultrapure water and ethanol to centrifuge and wash the precipitate. Collect the product and dry it in an oven at 60 ° C for 12 h to obtain CS@Cd powder.

[0009] S3. A glassy carbon electrode with a diameter of 3 mm was carefully polished to a mirror finish on suede with Al2O3 powder with a particle size of 0.05 μm, then placed in water and ultrasonically treated for 5 minutes; the prepared CS@Cd powder was mixed with 10 mL of a 1.0% (v / v) chitosan solution, and ultrasonically treated for 20 minutes to form a uniform dispersed solution, and then 2.5 μL of the dispersed solution was drop-coated on the glassy carbon electrode and naturally dried at room temperature to form a CS@Cd / GCE electrode.

[0010] The electrochemiluminescence sensor based on CS@Cd nanomaterials of the present invention can be used to detect catechol. During the detection, a three-electrode system is adopted, with CS@Cd / GCE electrode as the working electrode, Ag / AgCl (saturated KCl) as the reference electrode, and platinum wire as the auxiliary electrode.

[0011] Specifically, during the detection, the three-electrode system was immersed in a solution containing 1.00×10 -3 mol·L -1 Luminol, 1.00×10 - 3 mol·L -1 In a PBS solution of pH 7.5 containing H2O2 and a certain concentration of CA, the photomultiplier tube (PMT) multiplier high voltage was set to 700 V and the scan rate was set to 0.18 V·s -1 , the potential was scanned in the range of -0.5 to 1.5 V, the ECL reaction was triggered and the ECL light intensity was recorded, and then the linear regression equation was used: ΔI ECL =1.238lgC+14.19 to calculate the CA concentration, where ΔI ECL =I0-I, I0: ECL intensity of blank solution, I: ECL intensity after adding CA, C: CA concentration, r=0.9901; linear range is 1.0×10 -11 ~1.0×10 -4 mol·L -1 , the detection limit (S / N=3) is 2.5×10 -12 mol·L -1 .

[0012] The present invention has the following beneficial effects:

[0013] The method of the invention is simple and convenient to operate and has strong practicability. The synthesized CS@Cd nanocomposite material has a good ECL sensitization effect. The sensitivity of detecting CA using the CS@Cd / GCE electrode is high, and the detection limit can reach the picomolar order of magnitude. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0015] Figure 1 SEM images of CS (A) and CS@Cd (B)

[0016] Figure 2 TEM image of CS@Cd and surface distribution map of C, O, and Cd elements.

[0017] Figure 3 XPS spectra of CS@Cd. (A) Overall spectrum, (B) C 1s peak spectrum, (C) Cd 3d peak spectrum, and (D) O 1s peak spectrum.

[0018] Figure 4 ECL behavior for CS / GCE and CS@Cd / GCE.

[0019] Figure 5 (A) ECL curves with changes in CA concentration (a to p: 0, 1.0×10 -11 ,5.0×10 -11 ,1.0×10 -10 ,5.0×10 -10 ,1.0×10 -9 ,5.0×10 -9 ,1.0×10 -8 ,5.0×10 -8 ,1.0×10 -7 ,5.0×10 -7 ,1.0×10 -6 ,5.0×10 -6 ,1.0×10 -5 ,5.0×10 -5 ,1.0×10 -4 mol·L -1 ), (B) Working curve of ECL intensity attenuation value ΔI and lgC. DETAILED DESCRIPTION

[0020] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0021] Test data

[0022] Materials and instruments

[0023] Luminol, hydrogen peroxide, glucose, and catechol were purchased from China National Pharmaceutical Chemical Reagent Co., Ltd., and cadmium chloride, hexamethyltetramine, chitosan, acetic acid, nicotinic acid, and sodium hydroxide were purchased from Sigma-Aldrich Company, USA.

[0024] ECL detection was performed using an ultra-weak chemiluminescence / bioluminescence detector (ECL-9B, Nanjing Ebis Co., Ltd.) All electrochemical experiments used a conventional three-electrode system, in which GCE or modified electrode was used as the working electrode, Ag / AgCl (saturated KCl) as the reference electrode, and platinum wire as the auxiliary electrode.

[0025] Scanning electron microscopy images were characterized by a Regulus 8220 scanning electron microscope (SEM, Hitachi Ltd., Japan), high-resolution transmission electron microscopy images were characterized by a JEM-2100 projection electron microscope (HRTEM, JEOL Ltd., Japan), and X-ray photoelectron spectra were characterized by an ES-CALAB 250 X-ray photoelectron spectrometer (XPS, Thermo Ltd, USA).

[0026] Preparation of carbon spheres (CS)

[0027] 0.6486 g of glucose and 0.1108 g of nicotinic acid were dissolved in 18 mL of ultrapure water, and the resulting transparent solution was transferred to a 25 mL reactor for hydrothermal reaction at 200 ° C for 16 h. After cooling to room temperature, the suspended and precipitated brown powders were collected by centrifugation, then washed alternately with ultrapure water and ethanol several times, and finally dried in an oven at 70 ° C for 24 h to form CS powder.

[0028] Synthesis of CS@Cd nanocomposites

[0029] Dissolve 0.2284g of cadmium chloride in 20mL ultrapure water, add 0.02g of CS powder, ultrasonically treat for 30min, stir for 10min, slowly add 0.1402g of hexamethylenetetramine, continue stirring for 5h, alternately use ultrapure water and ethanol to centrifuge and wash the precipitate, and collect the product. Finally, the synthesized CS@Cd powder was dried in an oven at 60℃ for 12h. As can be seen from the SEM image, CS( Figure 1 A) and CS@Cd( Figure 1 B) is a smooth microsphere with an average diameter of about 400nm. Figure 2 From the TEM image, we can see that CS@Cd is a solid sphere, and the element surface distribution diagram shows that the surface of CS@Cd contains C, O and Cd elements. Figure 3 ) is used to analyze the composition and elements of CS@Cd. Figure 3 A) also proves the existence of elements C, O and Cd. Among them, the C 1s spectrum ( Figure 3 B) has three characteristic peaks, corresponding to CC (284.7 eV), CN (286.0 eV) and C=O (288.5 eV). Figure 3 C), the characteristic peaks at 405.40eV and 412.19eV are attributed to Cd 3d 5 / 2 and Cd 3d3 / 2 orbitals, respectively. The spin-orbit separation (Δ) of Cd 3d orbital is 6.79eV, indicating that cadmium exists mainly in the form of Cd(II). O 1s spectrum ( Figure 3 D) shows that characteristic peaks appear at 531.61 eV, 532.77 eV, and 533.70 eV, which are related to adsorbed oxygen (Oads), -CO, and C-OH, respectively.

[0030] Preparation of CS@Cd / GCE electrode

[0031] A glassy carbon electrode with a diameter of 3 mm was carefully polished to a mirror finish with Al2O3 (particle size 0.05 μm) powder on suede, then placed in water and ultrasonically treated for 5 min. The prepared CS@Cd powder and chitosan solution were mixed and ultrasonically treated for 20 min to form a uniform dispersion solution. Then 2.5 μL of the dispersion solution was dropped on the electrode and dried naturally at room temperature to form a CS@Cd / GCE electrode, which needed to be washed with PBS buffer before use.

[0032] ECL Test

[0033] The three-electrode system was immersed in a 1.00×10 -3 mol·L -1 Luminol, 1.00×10 -3 mol·L -1The photomultiplier tube (PMT) was set to 700 V with a scanning rate of 0.18 V·s -1 , scan the potential in the range of -0.5 to 1.5 V, trigger the ECL reaction and record the ECL light intensity.

[0034] Comparison of the ECL behaviors of CS / GCE and CS@Cd / GCE in the luminol-H2O2 system. Figure 4 It can be seen that the ECL signal of CS@Cd / GCE (curve a) is stronger than that of CS / GCE (curve c), which may be due to the sensitization effect of the CS@Cd composite material. When CA was added to the solution, the ECL signals of CS@Cd / GCE (curve b) and CS / GCE (curve d) decreased significantly because CA chemically consumed H2O2. This inhibitory effect can support the ECL detection of CA.

[0035] ECL sensor for quantitative detection of CA

[0036] Under the best detection conditions (scan rate of 0.18 V·s -1 ; pH 7.5), the linear relationship of CS@Cd / GCE to CA quantitative detection was studied. In the presence of different concentrations of CA, as the concentration of CA increased, the ECL intensity gradually decreased ( Figure 5 A). At the same time, the ECL intensity attenuation value (ΔI ECL ) has a good linear correlation with the logarithm of CA concentration ( Figure 5 B). The linear regression equation is ΔI ECL =1.238lgC+14.19(ΔI ECL =I0-I, I0: ECL intensity of blank solution, I: ECL intensity after adding CA; C: CA concentration, r=0.9901), the linear range is 1.0×10 -11 ~1.0×10 -4 mol·L -1 , the detection limit (S / N=3) is 2.5×10 - 12 mol·L -1 .

[0037] Selectivity and stability of ECL sensors

[0038] In order to study the selectivity of CS@Cd / GCE for CA, the -6 mol·L -1 Substances that may interfere were added to the CA solution. The results showed that 50-fold concentrations of lysine, arginine, valine, and threonine, 100-fold concentrations of glucose, ascorbic acid, urea, and Cu2+ and Ca 2+ There is no interference, which shows that CS@Cd / GCE has strong selectivity for CA.

[0039] After CS@Cd / GCE was stored at 4 °C for 15 days, CA was tested again. The ECL signal decayed by only 4.7% after 15 days, indicating that the stability of the ECL sensor was satisfactory.

[0040] Example 1

[0041] Place tea leaves (Lu'an Guapian) in an oven to dry the water and grind them into powder. Weigh 0.1g of tea powder, dissolve it in 30mL of 20% methanol aqueous solution, heat to 80°C and stir for 20min, filter and dilute the filtrate to 50mL. Perform detection according to the method of the present invention, and use the standard addition method to verify the reliability of the method. The results are shown in Table 1. The spiked recovery rate of CA is 98.0% to 103.5%, and the relative standard deviation (RSD) is 3.8% to 5.2%. It can be seen that the ECL sensor prepared by the present invention can be used for the detection of CA in actual samples.

[0042] Table 1 Determination of CA content in tea samples (n=7).

[0043]

[0044] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. An electrochemiluminescence sensor based on CS@Cd nanomaterials, characterized in that: Prepared by the following steps: S1. Take 0.6486 g of glucose and 0.1108 g of nicotinic acid, dissolve them in 18 mL of ultrapure water, transfer the resulting transparent solution to a 25 mL reactor, perform hydrothermal reaction at 200 °C for 16 h, cool to room temperature, collect the suspended and precipitated brown powder by centrifugation, wash them alternately with ultrapure water and ethanol several times, and dry them in an oven at 70 °C for 24 h to form CS powder; S2, dissolve 0.2284 g of cadmium chloride in 20 mL of ultrapure water, add 0.02 g of CS powder, ultrasonicate for 30 min, stir for 10 min, slowly add 0.1402 g of hexamethylenetetramine, continue stirring for 5 h, alternately use ultrapure water and ethanol to centrifuge and wash the precipitate, collect the product, and dry it in an oven at 60 ° C for 12 h to obtain CS@Cd powder; S3. A glassy carbon electrode with a diameter of 3 mm was carefully polished to a mirror finish on suede with Al2O3 powder with a particle size of 0.05 μm, then placed in water and ultrasonically treated for 5 min. The prepared CS@Cd powder was mixed with 10 mL of chitosan solution with a concentration of 1.0% v / v, and ultrasonically treated for 20 min to form a uniform dispersed solution. Then 2.5 μL of the dispersed solution was drop-coated on the glassy carbon electrode and dried naturally at room temperature to make a CS@Cd / GCE electrode.

2. The application of an electrochemiluminescence sensor based on CS@Cd nanomaterials as claimed in claim 1, characterized in that: Used to detect catechols.

3. The use according to claim 2, characterized in that: During detection, a three-electrode system was used, with CS@Cd / GCE electrode as the working electrode, Ag / AgCl / saturated KCl as the reference electrode, and platinum wire as the auxiliary electrode.

4. The use according to claim 3, characterized in that: During the detection, the three-electrode system was immersed in a solution containing 1.00×10 -3 mol·L -1 Luminol, 1.00×10 -3 mol·L -1 In a PBS solution of pH = 7.5 containing H2O2 and a certain concentration of CA, the multiplier voltage of the photomultiplier tube was set to 700 V and the scan rate was set to 0.18 V·s -1 , the potential was scanned in the range of -0.5 to 1.5 V, the ECL reaction was triggered and the ECL light intensity was recorded, and then the linear regression equation was used: ΔI ECL =1.238 lgC+14.19 to calculate the CA concentration, where ΔI ECL =I0-I, I0: ECL intensity of blank solution, I: ECL intensity after adding CA, C: CA concentration, r=0.9901; linear range is 1.0×10 -11 ~ 1.0×10 -4 mol·L -1 , the detection limit S / N = 3 is 2.5×10 -12 mol·L -1 .

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