Electrochemiluminescence sensor for detecting trace copper ions and detection method thereof

Abstract

The application belongs to the field of electrochemiluminescence sensors, and provides an electrochemiluminescence sensor for detecting trace copper ions and a detection method thereof. The electrochemiluminescence sensor for detecting trace copper ions adopts a three-electrode system, sulfur-nitrogen co-doped carbon dots are used as electrochemiluminescence bodies, persulfate is used as a co-reactant, a glassy carbon electrode is used as a working electrode, an Ag / AgCl electrode is used as a reference electrode, and a platinum sheet is used as an auxiliary electrode; electrochemiluminescence signals are excited to generate, and the quantitative relationship between the copper ion concentration and the electrochemiluminescence signal intensity of the sulfur-nitrogen co-doped carbon dots is constructed to detect the trace copper ion concentration.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electrochemiluminescence sensors, and particularly relates to an electrochemiluminescence sensor for detecting trace copper ions and a detection method thereof. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] Copper ions (Cu 2+ ) are essential trace elements for the human body, and their excess or deficiency is closely related to various serious diseases such as gastrointestinal disorders, liver and kidney damage, Menkes disease, prion disease and Wilson disease. In addition, as a common environmental heavy metal pollutant, copper ions are difficult to degrade and have high biological accumulation, enter the food chain through biological enrichment, and seriously threaten human health. Therefore, it is of great significance to develop a high-sensitivity trace copper ion detection technology, which can realize low-concentration detection and early warning of potential toxicity and biological accumulation risk.

[0004] Current commonly used detection technologies such as inductively coupled plasma mass spectrometry and atomic absorption spectrometry have high sensitivity but have problems such as complex operation, long detection time, expensive equipment, etc., and are difficult to meet the real-time and convenient detection requirements. The method for detecting copper ions using traditional electrochemiluminescence (ECL) technology mostly uses noble metal derivative materials as luminophores, which has the defects of poor biocompatibility and high material cost. In addition, the existing copper ion detection method based on electrochemiluminescence technology adopts an inhibitory mechanism, uses g-C3N4 nanotubes as electrochemiluminescence materials, and the detection limit for copper ions is 0.025 nM, and the detection range is 0.05-1000 nM. However, the synthesis process of g-C3N4 nanotubes is complex, which requires high-temperature calcination, grinding and long-time ultrasonic treatment, and the process is complicated and the manufacturing cost is high. In addition, g-C3N4 nanotubes have high impedance on the electrode interface and poor conductivity, which is difficult to meet the requirements of trace copper ion detection. In the inhibitory electrochemiluminescence mechanism, the chemiluminescence intensity decreases with the increase of copper ions, which requires higher photoelectric detection equipment. SUMMARY

[0005] In order to solve the technical problems in the background art, the present application provides an electrochemiluminescence sensor for detecting trace copper ions and a detection method thereof, which can meet the requirements of trace copper ion detection, effectively reduce the electrode impedance, and improve the performance of the sensor.

[0006] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0007] The first aspect of the present application provides an electrochemiluminescence sensor for detecting trace copper ions.

[0008] The application discloses an electrochemiluminescence sensor for detecting trace copper ions, which adopts a three-electrode system, sulfur-nitrogen co-doped carbon dots as an electrochemiluminescence body, a persulfate as a co-reactant, a glassy carbon electrode as a working electrode, an Ag / AgCl electrode as a reference electrode, and a platinum sheet as an auxiliary electrode, and excitation generates an electrochemiluminescence signal; and the concentration of trace copper ions is detected by establishing a quantitative relationship between the concentration of copper ions and the intensity of the electrochemiluminescence signal.

[0009] As an implementation form, the three-electrode system comprises a glassy carbon electrode as a working electrode, an Ag / AgCl electrode as a reference electrode, and a platinum sheet as an auxiliary electrode.

[0010] As an implementation form, the co-reactant is a 50 mM sodium persulfate solution.

[0011] As an implementation form, the co-reactant contains 50 μg·mL -1 of sulfur-nitrogen co-doped carbon dots (SN-CDs).

[0012] As an implementation form, the sulfur-nitrogen co-doped carbon dots are synthesized by both citric acid and L-cysteine by using a hydrothermal method.

[0013] As an implementation form, the preparation process of the sulfur-nitrogen co-doped carbon dots is as follows:

[0014] A certain amount of citric acid and L-cysteine is weighed and dissolved in distilled water, so that the molar ratio is 30:1, and then the mixture is transferred to a reaction kettle and heated at 180 DEG C for a certain time;

[0015] After the reaction is completed, the product is diluted twice with ethyl acetate, purified by liquid-liquid extraction to remove the precursor materials and part of the organic small molecules which do not participate in the reaction, and the ethyl acetate is removed in a rotary evaporator;

[0016] The final product is vacuum dried by a freeze dryer to obtain brown powder-like sulfur-nitrogen co-doped carbon dots (SN-CDs), which are stored in a 4 DEG C light-proof environment.

[0017] As an implementation form, the electrochemiluminescence signal is excited by using a cyclic voltammetry method or a linear sweep voltammetry method.

[0018] As an implementation form, the electrochemiluminescence sensor for detecting trace copper ions has a detection limit of 0.62 pM and a detection range of 1 pM to 1 nM.

[0019] The second aspect of the application provides a detection method of the electrochemiluminescence sensor for detecting trace copper ions as described above, which comprises:

[0020] The electrochemiluminescence signal intensity is enhanced with the higher concentration of copper ions, and a quantitative relationship between the concentration of copper ions and the electrochemiluminescence signal intensity is constructed in advance;

[0021] The sulfur-nitrogen co-doped carbon dots are contacted with the to-be-detected liquid, the electrochemiluminescence signal intensity is detected, and then the corresponding concentration of copper ions is calculated according to the quantitative relationship between the concentration of copper ions and the electrochemiluminescence signal intensity.

[0022] As an implementation manner, in the process of constructing the quantitative relationship between the concentration of copper ions and the electrochemiluminescence signal intensity of the sulfur-nitrogen co-doped carbon dots in advance, the potential scanning range is 0 to-1.8V, and the scanning rate is 0.1V·s -1 .

[0023] The present application has the following advantages:

[0024] (1) The present application adopts a three-electrode system, designs and synthesizes sulfur-nitrogen co-doped carbon dots as electrochemiluminescence (ECL) materials, wherein a glassy carbon electrode is used as a working electrode, an Ag / AgCl electrode is used as a reference electrode, and a platinum plate is used as an auxiliary electrode; an electrochemiluminescence signal is generated by exciting an electric signal; the sulfur-nitrogen co-doped carbon dots synthesized by citric acid and L-cysteine are used as a luminescent body, and copper ions are used as a co-reaction promoter, which significantly enhances the electrochemiluminescence signal intensity of the system, thereby realizing high-sensitivity detection of copper ions. The electrochemiluminescence signal intensity is enhanced with the higher concentration of copper ions, and a quantitative relationship between the concentration of copper ions and the luminescence signal intensity is constructed.

[0025] (2) The detection method of the present application is suitable for rapid detection of copper ions in a complex environment (such as seawater), and has the characteristics of safety, accuracy, high efficiency and simple operation. The detection range of the detection method of the present application for copper ions is 1pM to 1nM, and the detection limit can be as low as 0.62pM (S / N=3), which shows excellent sensitivity, safety, accuracy and convenience.

[0026] The advantages of the additional aspects of the present application will be partially given in the following description, partially will become obvious from the following description, or will be known by the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0027] The drawings accompanying the specification of the present application serve to provide a further understanding of the present application, and the schematic embodiments of the present application and the description thereof serve to explain the present application, and do not constitute an improper limitation on the present application.

[0028] Figure 1 is an electrochemiluminescence sensor principle for detecting trace copper ions;

[0029] Figure 2 is an electrochemiluminescence three-dimensional graph of the electrochemiluminescence signal intensity changing with the concentration of copper ions;

[0030] Figure 3 is a linear relationship diagram of electrochemiluminescence signal intensity changing with copper ion concentration. DETAILED DESCRIPTION

[0031] The application will be further described below in conjunction with the accompanying drawings and examples.

[0032] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0033] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0034] The present application aims to overcome the limitations of existing copper ion detection technology and proposes a copper ion detection method based on ECL. The electrochemiluminescence sensor of the present application is based on a sulfur-nitrogen co-doped carbon dot-persulfate ECL system. The sulfur-nitrogen co-doped carbon dot is used as the electrochemiluminescence body and the persulfate is used as the co-reactant. The copper ion enhances the electrochemiluminescence intensity of the system, and the enhancement effect is positively correlated with the copper ion concentration value, realizing sensitive detection of copper ions. The electrochemiluminescence sensor based on the present application can quickly and conveniently detect the concentration of copper ions. The present application first applies the ECL method using carbon dot material as the ECL emitter to the analysis and detection of trace copper ion concentration.

[0035] According to Figure 1 As shown in the figure, the embodiment of the present application provides an electrochemiluminescence sensor for detecting trace copper ions. A three-electrode system is adopted. The sulfur-nitrogen co-doped carbon dot is used as the electrochemiluminescence body, the persulfate is used as the co-reactant, the glassy carbon electrode is used as the working electrode, the Ag / AgCl electrode is used as the reference electrode, and the platinum sheet is used as the auxiliary electrode. The electrochemiluminescence signal is excited and generated. The quantitative relationship between the copper ion concentration and the electrochemiluminescence signal intensity is established to detect the trace copper ion concentration.

[0036] In this embodiment, the co-reactant is a 50mM sodium persulfate solution.

[0037] The co-reactant contains 50μg·mL -1 of sulfur-nitrogen co-doped carbon dots (SN-CDs).

[0038] The sulfur-nitrogen co-doped carbon dots are synthesized by both citric acid and L-cysteine using a hydrothermal method.

[0039] Specifically, the preparation process of the sulfur-nitrogen co-doped carbon dots is as follows:

[0040] A certain amount of citric acid (e.g., 3.8424 g) and L-cysteine (e.g., 0.08 g) are weighed and dissolved in distilled water (e.g., 10 mL) to obtain a molar ratio of 30:1. After mixing, the mixture is transferred to a reaction kettle and heated at 180°C for a certain period of time (e.g., 3 hours).

[0041] After the reaction is completed, the product is diluted twice with ethyl acetate and purified by liquid-liquid extraction to remove unreacted precursor materials and some small organic molecules. Ethyl acetate is removed in a rotary evaporator.

[0042] The final product is vacuum dried in a freeze dryer to obtain brown powder-like sulfur-nitrogen co-doped carbon dots (SN-CDs), which are stored in a 4°C light-proof environment.

[0043] The sulfur-nitrogen co-doped carbon dots of this embodiment have excellent electrochemical stability and strong electrochemiluminescence performance, and their synthesis process is simple and cost-effective. By introducing sulfur and nitrogen elements into the carbon dots, their electronic structure can be adjusted to optimize electron transfer performance, thereby improving their activity in electrochemical reactions. In addition, this structural regulation enables the sulfur-nitrogen co-doped carbon dots to maintain high stability under various environmental conditions and effectively reduce external interference.

[0044] In the sulfur-nitrogen co-doping system, L-cysteine, as an important dopant, introduces specific functional groups such as thiol and amine groups, which can synergize with the conversion reaction between copper ions and cuprous ions. Through this mechanism, the presence of copper ions can significantly enhance the electrochemiluminescence signal, and this enhancement effect is positively correlated with the concentration of copper ions.

[0045] Unlike metal complexes and quantum dots, sulfur-nitrogen co-doped carbon dots not only have good electrochemiluminescence properties, but also maintain stable performance in a wide range of pH values. In addition, due to its relatively simple synthesis process and low cost, sulfur-nitrogen co-doped carbon dots become an ideal alternative material, especially in applications requiring high sensitivity and low-cost electrochemical sensors, showing great advantages. Existing carbon nanotubes (CNTs) have excellent electrical conductivity, but their application in electrochemiluminescence sensors still faces many challenges, including difficulty in surface functionalization, poor solubility, and compatibility with electrode materials. In contrast, sulfur-nitrogen co-doped carbon dots not only have high electrical conductivity, but also can improve compatibility with electrode materials through reasonable surface modification, thereby improving the overall sensor performance.

[0046] In the embodiment, the three-electrode system comprises a glassy carbon electrode as a working electrode, an Ag / AgCl electrode as a reference electrode, and a platinum plate as an auxiliary electrode.

[0047] In some embodiments, the electrochemiluminescence signal is excited by cyclic voltammetry.

[0048] In other optional embodiments, the electrochemiluminescence signal is excited by linear sweep voltammetry or other existing methods such as constant potential method.

[0049] In the embodiment, the detection limit of the electrochemiluminescence sensor for detecting trace copper ions is 0.62 pM, and the detection range is 1 pM to 1 nM.

[0050] The detection method of the electrochemiluminescence sensor for detecting trace copper ions described above comprises:

[0051] According to the higher the concentration of copper ions, the electrochemiluminescence signal intensity is enhanced, and the quantitative relationship between the concentration of copper ions and the electrochemiluminescence signal intensity is constructed in advance, as shown in Figure 2 and Figure 3 .

[0052] The sulfur and nitrogen co-doped carbon dots are contacted with the to-be-measured liquid, the electrochemiluminescence signal intensity is detected, and then the corresponding concentration of copper ions is calculated from the quantitative relationship between the concentration of copper ions and the electrochemiluminescence signal intensity.

[0053] In the process of constructing the quantitative relationship between the concentration of copper ions and the electrochemiluminescence signal intensity of the sulfur and nitrogen co-doped carbon dots in advance, the potential scanning range is 0 to -1.8 V, and the scanning rate is 0.1 V·s -1 . The high voltage of the photomultiplier tube is set to 900 V.

[0054] The embodiment optimizes the experimental conditions to meet the high sensitivity and high signal-to-noise ratio requirements of trace copper detection, so that the sensor is more practical in complex environments. The detection method is suitable for rapid detection of copper ions in complex environments (such as seawater), and has the characteristics of safety, accuracy, efficiency and simple operation.

[0055] In the embodiment, the electrochemiluminescence substance carbon dots are directly added to the to-be-measured liquid, and a possible alternative is to fix the electrochemiluminescence substance carbon dots on the electrode surface, which can produce similar luminescence effect. By changing the synthesis conditions of carbon dots, electrochemiluminescence detection of copper ion concentration can also be realized.

[0056] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. An electrochemiluminescence sensor for detecting trace copper ions, characterized in that, It adopts a three-electrode system, sulfur-nitrogen co-doped carbon dots as electrochemiluminescence, persulfate as a co-reactant, glassy carbon electrode as the working electrode, Ag / AgCl electrode as the reference electrode, platinum plate as the auxiliary electrode, and the excitation generates electrochemiluminescence signal; The quantitative relationship between copper ion concentration and electrochemiluminescence signal intensity is established to detect trace copper ion concentration; The sulfur-nitrogen co-doped carbon dots are synthesized by both citric acid and L-cysteine using a hydrothermal method; The preparation process of the sulfur-nitrogen co-doped carbon dots is: A certain amount of citric acid and L-cysteine is weighed and dissolved in distilled water to make the molar ratio 30:1, then transferred to the reaction kettle after mixing, heated at 180°C for a certain time; After the reaction is completed, the product is diluted 2 times with ethyl acetate, purified by liquid-liquid extraction method to remove the precursor materials and part of the organic small molecules that do not participate in the reaction, and the ethyl acetate is removed in a rotary evaporator; The final product is vacuum dried by a freeze dryer to obtain brown powder sulfur-nitrogen co-doped carbon dots (SN-CDs), which are stored in a 4°C light-proof environment.

2. The electrochemiluminescence sensor for detecting trace copper ions according to claim 1, wherein, The co-reactant is: 50mM persulfate solution.

3. The electrochemiluminescence sensor for detecting trace copper ions according to claim 1, wherein, The co-reactant contains 50 sulfur-nitrogen co-doped carbon dots (SN-CDs).

4. The electrochemiluminescence sensor for detecting trace copper ions according to claim 1, wherein, The electrochemiluminescence signal is excited by cyclic voltammetry or linear sweep voltammetry.

5. The electrochemiluminescence sensor for detecting trace copper ions according to claim 1, wherein, The detection limit of the electrochemiluminescence sensor for detecting trace copper ions is 0.62pM.

6. The electrochemiluminescence sensor for detecting trace copper ions according to claim 1, wherein, The detection range of the electrochemiluminescence sensor for detecting trace copper ions is 1pM to 1nM.

7. A method for detecting a trace amount of copper ions using an electrochemiluminescence sensor according to any one of claims 1 to 6, characterized in that, It comprises: According to the higher the concentration of copper ions, the electrochemiluminescence signal intensity is enhanced, and the quantitative relationship between copper ion concentration and electrochemiluminescence signal intensity is established in advance; The sulfur-nitrogen co-doped carbon dots are contacted with the test solution, the electrochemiluminescence signal intensity is detected, and then the corresponding copper ion concentration is calculated from the quantitative relationship between copper ion concentration and electrochemiluminescence signal intensity.

8. The detection method of claim 7, wherein, In the process of constructing the quantitative relationship between the concentration of copper ions and the electrochemiluminescence signal intensity of sulfur-nitrogen co-doped carbon dots in advance, the potential scanning range is 0 to -1.8 V, and the scanning rate is 0.1 .

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