Electrochemical luminescence sensor for detecting trace copper ions and detection method thereof

Abstract

The invention belongs to the field of electrochemical luminescence sensors, and provides an electrochemical luminescence sensor for detecting trace copper ions and a detection method thereof. According to the electrochemical luminescence sensor for detecting the trace copper ions, a three-electrode system is adopted, sulfur-nitrogen co-doped carbon dots are used as an electrochemical luminophor, persulfate radicals are 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, so that an electrochemical luminescence signal is generated through excitation; the trace copper ion concentration is detected by constructing a quantitative relation between the copper ion concentration and the electrochemical luminescence signal intensity of the sulfur-nitrogen co-doped carbon dots.

Description

Technical Field

[0001] The invention belongs to the field of electrochemiluminescence sensors, and in particular relates to an electrochemiluminescence sensor for detecting trace copper ions and a detection method thereof. Background Art

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

[0003] Copper ion (Cu 2+ ) is an essential trace element for the human body. Its excess or deficiency is closely related to a variety of serious diseases such as gastrointestinal disorders, liver and kidney damage, Menkes disease, prion disease and Wilson disease. In addition, copper ions, as a common environmental heavy metal pollutant, enter the food chain through bioaccumulation due to its difficulty in degradation and high bioaccumulation, posing a serious threat to human health. Therefore, it is of great significance to develop a highly sensitive copper ion trace detection technology, which can realize low-concentration detection and early warning of potential toxicity and bioaccumulation risks.

[0004] Currently 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, and expensive equipment, which are difficult to meet the needs of real-time and convenient detection. The traditional electrochemiluminescence (ECL) technology is used to detect copper ions. Most of the precious metal derivatives are used as luminophores, which have defects such as poor biocompatibility and high material cost. In addition, the existing copper ion detection method based on electrochemiluminescence technology adopts an inhibitory mechanism, using g-C3N4 nanotubes as electrochemiluminescent materials, with a detection limit of 0.025nM for copper ions and a detection range of 0.05-1000nM. However, the synthesis process of g-C3N4 nanotubes is complicated, requiring high-temperature calcination, grinding and long-term ultrasonic treatment, and the process is cumbersome and the manufacturing cost is high. In addition, g-C3N4 nanotubes are prone to produce high impedance at the electrode interface and have poor conductivity, which is difficult to meet the requirements of trace copper ion detection. In the inhibitory electrochemiluminescence mechanism, the chemiluminescence intensity decreases as the copper ions increase, and higher requirements are placed on the photoelectric detection equipment. Summary of the invention

[0005] In order to solve the technical problems existing in the above-mentioned background technology, the present invention 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 electrode impedance, and improve sensor performance.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A first aspect of the present invention provides an electrochemiluminescent sensor for detecting trace amounts of copper ions.

[0008] An electrochemiluminescence sensor for detecting trace copper ions adopts a three-electrode system, sulfur-nitrogen co-doped carbon dots as electrochemiluminescent bodies, persulfate as co-reactants, a glassy carbon electrode as a working electrode, an Ag / AgCl electrode as a reference electrode, and a platinum sheet as an auxiliary electrode to excite and generate electrochemiluminescence signals; the trace copper ion concentration is detected by constructing a quantitative relationship between the copper ion concentration and the electrochemiluminescence signal intensity.

[0009] As an embodiment, the three-electrode system includes 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 embodiment, the co-reactant is: 50 mM sodium persulfate solution.

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

[0012] As an embodiment, the sulfur-nitrogen co-doped carbon dots are synthesized from citric acid and L-cysteine ​​using a hydrothermal method.

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

[0014] Weigh a set amount of citric acid and L-cysteine ​​respectively, dissolve them in distilled water to a molar ratio of 30:1, transfer them to a reactor after mixing, and heat at 180°C for a set time;

[0015] After the reaction, the product was diluted 2 times with ethyl acetate and purified by liquid-liquid extraction to remove the precursor materials and some small organic molecules that did not participate in the reaction, and the ethyl acetate was removed in a rotary evaporator;

[0016] The final product was vacuum dried in a freeze dryer to obtain brown powdery sulfur-nitrogen co-doped carbon dots (SN-CDs), which were stored at 4°C in a dark environment.

[0017] As an embodiment, cyclic voltammetry or linear sweep voltammetry is used to excite and generate electrochemiluminescence signals.

[0018] As an 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.

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

[0020] According to the fact that the electrochemiluminescence signal intensity increases with the increase of copper ion concentration, a quantitative relationship between copper ion concentration and electrochemiluminescence signal intensity is pre-established;

[0021] The sulfur-nitrogen co-doped carbon dots are brought into contact with the test solution, the electrochemiluminescence signal intensity is detected, and then the corresponding copper ion concentration is calculated from the quantitative relationship between the copper ion concentration and the electrochemiluminescence signal intensity.

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

[0023] The beneficial effects of the present invention are:

[0024] (1) The present invention 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 sheet is used as an auxiliary electrode; an electrochemiluminescence signal is generated by excitation of an electrical signal; sulfur-nitrogen co-doped carbon dots synthesized by citric acid and L-cysteine ​​are used as luminophores, and copper ions are used as co-reaction promoters to significantly enhance the electrochemiluminescence signal intensity of the system, thereby achieving high-sensitivity detection of copper ions. The higher the copper ion concentration, the stronger the electrochemiluminescence signal intensity, based on which a quantitative relationship between copper ion concentration and luminescence signal intensity is constructed.

[0025] (2) The detection method of the present invention is suitable for the rapid detection of copper ions in complex environments (such as seawater), and is safe, accurate, efficient and easy to operate. The detection range of the detection method of the present invention for copper ions is 1pM to 1nM, and the detection limit can be as low as 0.62pM (S / N=3), showing excellent sensitivity, safety, accuracy and convenience.

[0026] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0028] Figure 1 It is the principle of electrochemiluminescence sensor used to detect trace copper ions;

[0029] Figure 2 It is a three-dimensional electrochemiluminescence graph showing the electrochemiluminescence signal intensity changing with the copper ion concentration;

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

[0031] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0032] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

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

[0034] The present invention 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 invention is based on a sulfur-nitrogen co-doped carbon dot-persulfate ECL system, using sulfur-nitrogen co-doped carbon dots as electrochemiluminescent bodies and persulfate as co-reactants, and using copper ions to enhance the electrochemiluminescence intensity of the system. The enhancement effect is positively correlated with the copper ion concentration value, thereby realizing sensitive detection of copper ions. The electrochemiluminescence sensor based on the present invention can quickly and conveniently detect the concentration of copper ions. The present invention is the first to apply the ECL method using carbon dot materials as ECL luminescent bodies to the analytical detection of trace copper ion concentrations.

[0035] according to Figure 1 As shown, an embodiment of the present invention provides an electrochemiluminescence sensor for detecting trace copper ions, which adopts a three-electrode system, sulfur-nitrogen co-doped carbon dots as electrochemiluminescent bodies, persulfate as co-reactants, glassy carbon electrodes as working electrodes, Ag / AgCl electrodes as reference electrodes, and platinum sheets as auxiliary electrodes to excite and generate electrochemiluminescence signals; the trace copper ion concentration is detected by constructing a quantitative relationship between the copper ion concentration and the electrochemiluminescence signal intensity.

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

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

[0038] The sulfur-nitrogen co-doped carbon dots are synthesized from 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] Weigh a set amount of citric acid (e.g., 3.8424 g) and L-cysteine ​​(e.g., 0.08 g), dissolve them in distilled water (e.g., 10 ml) to a molar ratio of 30:1, transfer them to a reactor after mixing, and heat at 180° C. for a set time (e.g., 3 hours);

[0041] After the reaction, the product was diluted 2 times with ethyl acetate and purified by liquid-liquid extraction to remove the precursor materials and some small organic molecules that did not participate in the reaction, and the ethyl acetate was removed in a rotary evaporator;

[0042] The final product was vacuum dried in a freeze dryer to obtain brown powdery sulfur-nitrogen co-doped carbon dots (SN-CDs), which were stored at 4°C in a dark 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 low-cost. By introducing sulfur and nitrogen elements into carbon dots, their electronic structure can be adjusted and the electron transfer performance can be optimized, thereby improving their activity in electrochemical reactions. In addition, this structural regulation enables sulfur-nitrogen co-doped carbon dots to maintain high stability under various environmental conditions and effectively reduce the interference of external factors.

[0044] In the sulfur-nitrogen co-doping system, L-cysteine ​​is used as an important dopant to introduce 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 over a wide pH range. In addition, due to its relatively simple synthesis process and low cost, sulfur-nitrogen co-doped carbon dots have become an ideal alternative material, especially in electrochemical sensor applications that require high sensitivity and low cost. Although existing carbon nanotubes (CNTs) have excellent conductive properties, their application in electrochemiluminescence sensors still faces many challenges, including the difficulty of surface functionalization, poor solubility, and compatibility issues with the electrode interface. In contrast, sulfur-nitrogen co-doped carbon dots not only have higher conductivity, but also can improve compatibility with electrode materials through reasonable surface modification, thereby improving the overall sensor performance.

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

[0047] In some embodiments, the electrochemiluminescent signal is generated using cyclic voltammetry excitation.

[0048] In some other optional embodiments, other existing methods such as linear sweep voltammetry or constant potential method are used to excite and generate electrochemiluminescence signals.

[0049] In this 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 based on the electrochemiluminescence sensor for detecting trace copper ions described above comprises:

[0051] As the copper ion concentration increases, the electrochemiluminescence signal intensity increases accordingly, and a quantitative relationship between the copper ion concentration and the electrochemiluminescence signal intensity is pre-established, such as Figure 2 and Figure 3 As shown;

[0052] The sulfur-nitrogen co-doped carbon dots are brought into contact with the test solution, the electrochemiluminescence signal intensity is detected, and then the corresponding copper ion concentration is calculated from the quantitative relationship between the copper ion concentration and the electrochemiluminescence signal intensity.

[0053] In the process of pre-constructing the quantitative relationship between the copper ion concentration and the electrochemiluminescence signal intensity of sulfur-nitrogen co-doped carbon dots, the potential scanning range was 0 to -1.8 V, the scanning rate was 0.1 V s-1, and the high voltage of the electromultiplier tube was set to 900V.

[0054] This embodiment optimizes the experimental conditions to meet the high sensitivity and high signal-to-noise ratio requirements for trace copper detection, making the application of the sensor in complex environments more practical. The detection method is suitable for rapid detection of copper ions in complex environments (such as seawater), and is safe, accurate, efficient and easy to operate.

[0055] In the embodiment of the present invention, the electrochemiluminescent carbon dots are directly added to the test solution. A possible alternative is to fix the electrochemiluminescent carbon dots on the electrode surface, which can produce a similar luminescent effect. By changing the carbon dot synthesis conditions, electrochemiluminescent detection of copper ion concentration can also be achieved.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An electrochemiluminescent sensor for detecting trace copper ions, characterized in that: It adopts a three-electrode system, with sulfur-nitrogen co-doped carbon dots as electrochemiluminescent bodies, persulfate as co-reactant, glassy carbon electrode as working electrode, Ag / AgCl electrode as reference electrode, and platinum sheet as auxiliary electrode to stimulate and generate electrochemiluminescent signals; trace copper ion concentration is detected by constructing a quantitative relationship between copper ion concentration and electrochemiluminescent signal intensity.

2. The electrochemiluminescent sensor for detecting trace copper ions according to claim 1, characterized in that: The three-electrode system includes a glassy carbon electrode as a working electrode, an Ag / AgCl electrode as a reference electrode, and a platinum sheet as an auxiliary electrode.

3. The electrochemiluminescent sensor for detecting trace copper ions according to claim 1, characterized in that: The co-reactant is: 50 mM persulfate solution.

4. The electrochemiluminescent sensor for detecting trace copper ions according to claim 1, characterized in that: The co-reactant contained 50 μg mL-1 of sulfur-nitrogen co-doped carbon dots (SN-CDs).

5. The electrochemiluminescent sensor for detecting trace copper ions according to claim 1, characterized in that: The sulfur-nitrogen co-doped carbon dots are synthesized from citric acid and L-cysteine ​​using a hydrothermal method.

6. The electrochemiluminescent sensor for detecting trace copper ions according to claim 5, characterized in that: The preparation process of the sulfur-nitrogen co-doped carbon dots is as follows: Weigh a set amount of citric acid and L-cysteine ​​respectively, dissolve them in distilled water to a molar ratio of 30:1, transfer them to a reactor after mixing, and heat at 180°C for a set time; After the reaction, the product was diluted 2 times with ethyl acetate and purified by liquid-liquid extraction to remove the precursor materials and some small organic molecules that did not participate in the reaction, and the ethyl acetate was removed in a rotary evaporator; The final product was vacuum dried in a freeze dryer to obtain brown powdery sulfur-nitrogen co-doped carbon dots (SN-CDs), which were stored at 4°C in a dark environment.

7. The electrochemiluminescent sensor for detecting trace copper ions according to claim 1, characterized in that: The electrochemiluminescence signal was generated by cyclic voltammetry or linear sweep voltammetry.

8. The electrochemiluminescent sensor for detecting trace copper ions according to claim 1, characterized in that: The detection limit of the electrochemiluminescent sensor for detecting trace copper ions is 0.62 pM, and the detection range is 1 pM to 1 nM.

9. A detection method for an electrochemiluminescent sensor for detecting trace copper ions as claimed in any one of claims 1 to 8, characterized in that: include: According to the fact that the electrochemiluminescence signal intensity increases with the increase of copper ion concentration, a quantitative relationship between copper ion concentration and electrochemiluminescence signal intensity is pre-established; The sulfur-nitrogen co-doped carbon dots are brought into contact with the test solution, the electrochemiluminescence signal intensity is detected, and then the corresponding copper ion concentration is calculated from the quantitative relationship between the copper ion concentration and the electrochemiluminescence signal intensity.

10. The detection method according to claim 9, characterized in that: In the process of pre-constructing the quantitative relationship between the copper ion concentration and the electrochemiluminescence signal intensity of sulfur-nitrogen co-doped carbon dots, the potential scanning range was 0 to -1.8 V, and the scanning rate was 0.1 V s-1.

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