CN104155289A - Solid electrochemical luminescence sensor for detecting mercury ions and preparation method and application of solid electrochemical luminescence sensor for detecting mercury ions - Google Patents

Abstract

The invention discloses a solid-state electrochemiluminescence sensor for mercury ion detection and its preparation method and application. Hg ²⁺ -T mismatched DNA2 and biotin glassy carbon electrode; its preparation method includes the preparation steps of the DNA1 glassy carbon electrode and the assembly step of the solid-state electrochemiluminescence sensor, which has the advantages of high sensitivity and stability Good, strong selectivity, good reproducibility, easy to operate, saving reagents, etc.

Description

A solid-state electrochemiluminescence sensor for detecting mercury ions and its preparation method and application

technical field

The invention relates to the technical field of heavy metal detection, in particular to a solid-state electrochemical luminescence sensor for detecting mercury ions, a preparation method and application thereof.

Background technique

Heavy metal pollution is one of the important components of environmental pollution. Mercury (Hg), the only liquid metal at room temperature, is the number one killer of heavy metal pollution. In recent years, the mining, smelting, processing and commercial manufacturing activities of heavy metal mercury have been increasing, and a large amount of mercury has entered the atmosphere, water and soil for retention, accumulation and migration. Mercury in the environment finally enters the body of animals and humans in the form of food chain, causing great damage to the vital functions of organisms, and causing diseases such as neuropsychiatric symptoms, tremors, stomatitis, and toxic nephropathy. Mercury ion (Hg ²⁺ ) is one of the main forms of mercury in nature, and it is not required to be detected in many health standards. Therefore, the development of high-sensitivity and high-selectivity low-concentration mercury ion detection methods is essential for environmental testing and food safety monitoring. is of great significance.

At present, the methods for detecting mercury ions mainly include: cold atomic absorption spectrometry, ICP-MS, fluorescence spectrometry, ultraviolet-visible spectrophotometry, atomic fluorescence method, electrochemical method, ion chromatography, capillary electrophoresis method, heavy metal rapid detector method, test strip method, etc., but these methods may need to use expensive instruments, cumbersome operations, and require testing personnel to have certain professional knowledge, high analysis costs, difficult to popularize; or low sensitivity, poor selectivity, complicated sample pretreatment , it is difficult to accurately quantitatively detect low-concentration Hg ²⁺ .

Electrochemiluminescence (ECL) is an analytical technique that combines electrochemistry and chemiluminescence. It not only has the advantages of high sensitivity, wide linear range, convenient observation, and simple instruments, but also has the advantages of electrochemical analysis. Potential controllability, high selectivity, stable reagents, and good reproducibility have attracted great attention from scientific researchers, and have gradually developed into an important branch of the field of analysis and detection. Solid-state electrochemiluminescence is a technology in which electrochemiluminescent reagents are immobilized on the surface of electrodes by chemical or physical methods and then detected by ECL. Compared with ECL in solution, solid-state ECL constructed by immobilizing electrochemiluminescent reagents on the electrode surface , and the following advantages: reduce the amount of expensive reagents, simplify experimental operations, improve ECL intensity, etc. However, at present, there is no published report on the use of N-(4-aminobutyl)-N-ethylisoluminol (ABEI) for the detection of mercury ion content in water by solid-state electrochemiluminescence.

Contents of the invention

The technical problem to be solved by the present invention is to provide a solid-state electrochemiluminescence sensor for mercury ion detection with high sensitivity, good stability, strong selectivity, good reproducibility and easy operation, as well as its preparation method and detection method.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a solid-state electrochemical luminescence sensor for detecting mercury ions, the sensor is ABEI with solid-carrying electropolymerization on the surface, and then sequentially assembled with glutaraldehyde, DNA1, Glassy carbon electrode with DNA2 bound by T-Hg ²⁺ -T mismatch and biotin.

The preparation method of the above-mentioned solid-state electrochemiluminescence sensor for detecting mercury ions, the specific steps are as follows:

(1) Preparation of glassy carbon electrode immobilized with DNA1

a. Polish the glassy carbon electrode with a diameter of 3-5 mm with aluminum oxide of 1.0 μm, 0.3 μm, and 0.05 μm in sequence, then ultrasonically clean it with ethanol and water in sequence, rinse it with water, and dry it with nitrogen for later use;

b. Place the glassy carbon electrode obtained in step (a) in the H ₂ SO ₄ solution containing N-(4-aminobutyl)-N-ethylisoluminol (ABEI), and perform cyclic voltammetry scanning. The range is ?0.2-1.5 V, and the scanning speed is 0.01-0.1 V/s to scan 20-30 times, so that ABEI is electropolymerized on the surface of the glassy carbon electrode; the said N-(4-aminobutyl)-N -The concentration of N-(4-aminobutyl)-N-ethylisoluminol (ABEI) in H ₂ SO ₄ solution is 0.01～0.0001 mol/L, H ₂ SO ₄ The concentration is 0.1-1 mol/L;

c. After washing the glassy carbon electrode obtained in step (b) with 0.01-0.1 M PBS buffer solution with pH = 7-8, add 10-20 μL of 1-3 wt% glutaraldehyde solution dropwise on the surface of the glassy carbon electrode, Stand for 20-40 minutes;

d. After washing the glassy carbon electrode obtained in step (c) with 0.01-0.1 M PBS buffer solution with pH = 7-8, add 0.01 ~ 10 ~ 20 μL of 0.1 M PBS buffer solution, let stand for 20 ~ 40 min to make DNA1 bind to the electrode surface;

e. Soak the glassy carbon electrode obtained in step (d) in 10-20 μL bovine serum albumin solution with a concentration of 2% by mass, and block it for 1-2 hours (blocking the inactive sites), and the solid-loaded Glassy carbon electrode of DNA1;

(2) Assembly of solid-state electrochemiluminescence sensor

a. Prepare a series of standard solutions containing mercury ions with different concentrations, and mix the standard solution with 0.01-0.1 M PBS buffer solution containing 10 μmol/L DNA2 and pH = 7-8 at a volume ratio of 1:1;

b. Take 10-20 μL of the mixed solution obtained in step (a) and drop it on the surface of the glassy carbon electrode loaded with DNA1. Buffer washing;

c. Take an appropriate amount of 0.01-0.1 M PBS buffer solution with pH = 7-8 to prepare 0.01-0.1 mg/mL avidin solution, and add 10-20 μL of avidin solution dropwise to the surface of the glassy carbon electrode obtained in step (b). After incubation for 5 min;

d. After the glassy carbon electrode obtained in step (c) is washed with 0.01-0.1 M PBS buffer solution with pH = 7-8, a solid-state electrochemiluminescence sensor for mercury ion detection is obtained.

The structural formula of DNA1 is: 5'-NH ₂ -(CH ₂ ) ₆ -GAC T GTC T CGT T CGC T TAG-3'; the structural formula of DNA2 is: 5'-biotin-CTA T GCG T ACG T GAC T GTC-3'.

The method for detecting mercury ions of the above-mentioned solid-state electrochemiluminescence sensor, the specific steps are as follows:

(1) Standard curve establishment

a. after the glassy carbon electrode that is loaded with DNA1 described in claim 3 is rinsed clean with 0.01～0.1 M PBS buffer solution, in the 0.05～0.2 M carbonate buffer solution of pH=9～10, start electrochemical Reaction, test electrochemiluminescence intensity I ₀ ;

b. the solid-state electrochemiluminescence sensor for mercury ion detection described in claim 3 is put into 0.05～0.2 M carbonate buffer solution of pH=9～10, starts electrochemical reaction, measures electrochemiluminescence intensity, obtains The electrochemiluminescence intensity value I ₁ corresponding to a series of different concentrations of Hg ²⁺ solutions, calculate the change value of the electrochemiluminescence intensity of a series of different concentrations of Hg ²⁺ solutions ΔI= I ₀ ?I ₁ , and establish the value of the electrochemiluminescence intensity Change the quantitative relationship between the value ΔI and the concentration of the Hg ²⁺ solution;

(2) Determination of samples to be tested

a. Mix the sample solution to be tested containing mercury ions with 0.01-0.1 M PBS buffer solution of pH 7-8 containing 10 μmol/L DNA2 at a volume ratio of 1:1;

b. Take 10-20 μL of the mixed solution obtained in step (a) and drop it on the surface of the glassy carbon electrode loaded with DNA1. Buffer washing;

c. Add 10-20 μL of 0.01-0.1 mg/mL avidin solution prepared in 0.01-0.1 M PBS buffer solution with pH = 7-8 to the surface of the glassy carbon electrode obtained in step (b), and incubate for 5 min;

d. After cleaning the glassy carbon electrode obtained in step (c) with 0.01-0.1 M PBS buffer solution with pH = 7-8, it is used as a working electrode, a saturated calomel electrode or an Ag/AgCl electrode is used as a reference electrode, and a platinum wire electrode is used as a counter electrode. Electrode, build a three-electrode system, put it into a 0.05-0.2 M carbonate buffer solution with pH = 9-10, start the electrochemical reaction, test the value of the intensity of the electrochemiluminescence, and use the change value of the intensity of the electrochemiluminescence ΔI and Hg ^{2 +} The quantitative relationship between the concentration of the solution is calculated to obtain the accurate concentration C _Hg of Hg ²⁺ in the sample solution to be tested.

The carbonate buffer solution contains 1 mM hydrogen peroxide, and the electrochemical method used is potential step chronoamperometry; potential step: 0 V step to 1 V; pulse width: 0.25 s; measurement time Interval: 30 s.

Invention principle: The electrochemiluminescence reagent is electropolymerized ABEI. After ABEI is electropolymerized on the surface of the glassy carbon electrode, the original two-step electrochemiluminescence reaction becomes one step, and the electrochemiluminescence signal is very stable from irreversible to reversible. The amino groups in ABEI are still retained, which is very convenient for subsequent coupling of DNA. Under the action of glutaraldehyde cross-linking, the amino group of DNA1 is coupled with the amino group in the ABEI polymer on the electrode surface, thereby being immobilized on the electrode surface. At this time, the measured electrochemiluminescent intensity I ₀ is very large. When there is Hg ²⁺ in the solution to be tested, DNA1 and DNA2 are combined through T-Hg ²⁺ -T mismatch, and avidin binds to biotin at the end of DNA2. Biotin is a biological macromolecule with a molecular weight of about 60kD. The surface of the electrode can effectively hinder the transmission of electrons and light, and weaken the electrochemiluminescence to I ₁ . The higher the content of Hg ²⁺ in the solution to be tested, the greater the change value of luminous intensity ΔI=I ₀ ?I ₁ , which is the mechanism of the solid-state electrochemiluminescence sensor for quantitative detection of Hg ²⁺ . The schematic diagram of the solid-state ECL sensor for Hg2 ⁺ detection is shown in Fig. 1.

Compared with the prior art, the present invention has the advantages of:

(1) High sensitivity. With the help of the extremely high sensitivity of the electrochemiluminescence technology itself, this solid-state electrochemiluminescence sensor can quantitatively detect 0.01 nM Hg ²⁺ .

(2) High selectivity, common metal ions such as Pb ²⁺ , Mn ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Zn ²⁺ , Cd ²⁺ , Mg ²⁺ do not interfere with the detection. The reason is that the T-Hg ²⁺ -T mismatch has a high specificity in identifying mercury ions, and the interference of other metal ions is negligible.

(3) Low cost. The amount of reagent required is minimal.

(4) High precision. Using solid-state electrochemiluminescence, the signal is stable and the result precision is high.

In summary, the present invention intends to prepare a solid-state electrochemiluminescence sensor for mercury ion detection, which has the advantages of high sensitivity, good stability, strong selectivity, good reproducibility, and easy operation, and can achieve ultra-low The detection purpose of the concentration of mercury ions.

Description of drawings

Fig. 1 is the schematic diagram of the detection of mercury ions by the solid-state electrochemiluminescence sensor of the present invention;

Figure 2 is the electrochemiluminescent signal corresponding to different concentrations of mercury ions;

Fig. 3 is a linear relationship diagram between the change value ΔI of the luminous intensity and the logarithm of the mercury ion concentration;

Fig. 4 is a graph showing the selective detection results of mercury ions detected by the solid-state electrochemiluminescent sensor of the present invention.

Detailed ways

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

Specific embodiment one

A solid-state electrochemiluminescent sensor for detecting mercury ions. The sensor is surface-mounted electropolymerized ABEI, and then sequentially assembled with glutaraldehyde, DNA1, DNA2 through T-Hg ²⁺ -T mismatch binding, and biological A plain glassy carbon electrode, the specific preparation steps are as follows:

(1) Preparation of glassy carbon electrode immobilized with DNA1

a. Polish the glassy carbon electrode with a diameter of 3-5 mm with aluminum oxide of 1.0 μm, 0.3 μm, and 0.05 μm in sequence, then ultrasonically clean it with ethanol and water in sequence, rinse it with water, and dry it with nitrogen for later use;

b. Place the glassy carbon electrode obtained in step (a) in the H ₂ SO ₄ solution containing N-(4-aminobutyl)-N-ethylisoluminol (ABEI), and perform cyclic voltammetry scanning. The range is ?0.2～1.5 V, and the scanning speed is 0.05 V/s for 20 cycles, so that ABEI is electropolymerized on the surface of the glassy carbon electrode; the above-mentioned N-(4-aminobutyl)-N-ethylisoluminami The concentration of N-(4-aminobutyl)-N-ethyl isoluminol (ABEI) in the H ₂ SO ₄ solution of ABEI is 0.001 mol/L, and the concentration of H ₂ SO ₄ is 0.1 ~ 1 mol/L L;

c. After washing the glassy carbon electrode obtained in step (b) with 0.01-0.1 M PBS buffer solution with pH = 7-8, add 10-20 μL of 1-3 wt% glutaraldehyde solution dropwise on the surface of the glassy carbon electrode, Stand for 20-40 minutes;

d. After washing the glassy carbon electrode obtained in step (c) with 0.01-0.1 M PBS buffer solution with pH = 7-8, dropwise add 0.01 M solution with pH = 7-8 containing 10 μmol/L DNA1 ～0.1 M PBS buffer 10～20 μL, let stand for 20～40 min, make DNA1 bind to the electrode surface; the structural formula of DNA1 is: 5'-NH ₂ -(CH ₂ ) ₆ -GAC T GTC T CGT T CGC T TAG-3';

e. Soak the glassy carbon electrode obtained in step (d) in 10-20 μL bovine serum albumin solution with a concentration of 2% by mass, and block it for 1-2 hours (blocking the inactive sites), and the solid-loaded Glassy carbon electrode of DNA1;

(2) Assembly of solid-state electrochemiluminescence sensor

a. Prepare a series of standard solutions containing mercury ions with different concentrations, and mix the standard solution with 0.01-0.1 M PBS buffer solution containing 10 μmol/L DNA2 at pH = 7-8 at a volume ratio of 1:1; The structural formula is: 5'-biotin-CTA T GCG T ACG T GAC T GTC-3';

b. Take 10-20 μL of the mixed solution obtained in step (a) and drop it on the surface of the glassy carbon electrode loaded with DNA1. Buffer washing;

c. Take an appropriate amount of 0.01-0.1 M PBS buffer solution with pH = 7-8 to prepare 0.01-0.1 mg/mL avidin solution, and add 10-20 μL of avidin solution dropwise to the surface of the glassy carbon electrode obtained in step (b). After incubation for 5 min;

d. After the glassy carbon electrode obtained in step (c) is washed with 0.01-0.1 M PBS buffer solution with pH = 7-8, a solid-state electrochemiluminescence sensor for mercury ion detection is obtained.

In addition to the above-mentioned specific examples, in the steps of preparing the above-mentioned solid-state electrochemiluminescence sensor:

The scan rate of cyclic voltammetry scan can also be any value within 0.01～0.1 V/s, and the number of circles can also be any value within 20～30 circles, including N-(4-aminobutyl)-N- The concentration of N-(4-aminobutyl)-N-ethylisoluminol (ABEI) in the H ₂ SO ₄ solution of ethyl isoluminol (ABEI) can also be any value within 0.01 ~ 0.0001 mol/L One value, the concentration of H ₂ SO ₄ can be any value within 0.1 ~ 1 mol/L;

The concentration of glutaraldehyde solution can be any value within 1-3 wt%, the drop volume can be any value within 10-20 μL, and the standing time can be any value within 20-40 minutes;

The volume of 0.01-0.1 M PBS buffer containing 10 μmol/L DNA1 and pH = 7-8 can be any value within 10-20 μL, and the standing time can be any value within 20-40 minutes ;

The adding volume of bovine serum albumin (BSA) solution can be any value within 10-20 μL, and the standing time can be any value within 1-2 h;

The standard solution and 0.01-0.1 M PBS buffer solution containing 10 μmol/L DNA2 at pH = 7-8 are mixed at a volume ratio of 1:1, and the volume of the mixed solution added dropwise to the surface of the glassy carbon electrode immobilized with DNA1 can be Any value of 10-20 μL, and the incubation time can be any value within 20-30 min;

The concentration of avidin solution can be any value within 0.01-0.1 mg/mL, and the dropping volume can be any value within 10-20 μL;

The concentration of PBS buffer can be any value within 0.01-0.1 M, and the pH can be any value within 7-8.

Specific embodiment two

The method for detecting mercury ions using the solid-state electrochemiluminescence sensor prepared in the above specific embodiment two, the principle of detecting mercury ions is shown in Figure 1, and the specific steps are as follows:

a. After washing the glassy carbon electrode immobilized with DNA1 prepared in the above specific example 2 with 0.01-0.1 M PBS buffer solution, start the process in 0.05-0.2 M carbonate buffer solution with pH = 9-10 Electrochemical reaction, testing the intensity of electrochemiluminescence I ₀ ;

b. Put the solid-state electrochemiluminescence sensor for mercury ion detection prepared in the above specific example 2 into 0.05-0.2 M carbonate buffer solution with pH = 9-10, start the electrochemical reaction, and measure the intensity of electrochemiluminescence , to obtain the ECL intensity value I ₁ corresponding to a series of Hg ²⁺ solutions with different concentrations, and calculate the change value of the ECL intensity for a series of Hg ²⁺ solutions with different concentrations ΔI= I ₀ ?I ₁ ,

The change value of the electrochemiluminescence intensity ΔI= I ₀ ?I ₁ , has a linear relationship with the logarithm of the mercury ion concentration in the concentration range of 0.01 to 10 nM (the electrochemiluminescence signals corresponding to different concentrations of mercury ions are shown in Figure 2) , the standard curve is ΔI= 2493.25 + 843.63 log C _Hg (nM) (the linear relationship between the change value of luminous intensity ΔI and the logarithm of the mercury ion concentration is shown in Figure 3);

(2) Determination of samples to be tested

a. Mix the sample solution to be tested containing mercury ions with 0.01-0.1 M PBS buffer solution of pH 7-8 containing 10 μmol/L DNA2 at a volume ratio of 1:1;

b. Take 10-20 μL of the mixed solution obtained in step (a), drop it on the surface of the glassy carbon electrode immobilized with DNA1 prepared in the above specific example 1, incubate at room temperature for 20-30 min, and use pH = 7 Wash with 0.01-0.1 M PBS buffer solution of ~8;

c. Add 10-20 μL of 0.01-0.1 mg/mL avidin solution prepared in 0.01-0.1 M PBS buffer solution with pH = 7-8 to the surface of the glassy carbon electrode obtained in step (b), and incubate for 5 min;

d. After cleaning the glassy carbon electrode obtained in step (c) with 0.01-0.1 M PBS buffer solution with pH = 7-8, it is used as a working electrode, a saturated calomel electrode or an Ag/AgCl electrode is used as a reference electrode, and a platinum wire electrode is used as a counter electrode. Electrode, build a three-electrode system, put it into the 0.05-0.2 M carbonate buffer solution with pH = 9-10, start the electrochemical reaction, test the value of the electrochemiluminescence intensity, according to the standard curve ΔI= 2493.25 + 843.63 log C _Hg ( nM), calculate the accurate concentration _CHg of Hg ²⁺ in the sample solution to be tested, and the unit is nM.

The above-mentioned carbonate buffer solution contains 1 mM hydrogen peroxide, and the electrochemical method used is potential step chronoamperometry; potential step: 0 V step to 1 V; pulse width: 0.25 s; measurement time interval: 30 s.

Specific embodiment three

Highly selective and sensitive detection assay

The high sensitivity is reflected in the specific embodiment 2. Since the change value of the electrochemiluminescent intensity ΔI=I ₀ ?I ₁ has a linear relationship with the logarithm of the mercury ion concentration within the concentration range of 0.01 to 10 nM, the specific embodiment 1 The prepared solid-state ECL sensor for detecting mercury ions has a detection sensitivity of 0.01 nM for Hg ²⁺ .

High selectivity: under the same experimental conditions as in the above specific example 2, common interfering ions at 10 μM are detected: Pb ²⁺ , Mn ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Zn ²⁺ , Cd ²⁺ , Mg ²⁺ , the results are shown in Figure 4.

The results show that: 0.01 nM Hg ²⁺ causes the ΔI of the sensor to be about 800, while 10 μM common interfering ions cause the ΔI of the sensor to be less than 200, which means that 1000000 times common interfering ions do not affect the detection. The main reason is that Hg ²⁺ and T-Hg ²⁺ -T mismatch between T bases, specific recognition between biotin and avidin.

Specific embodiment four

Using the solid-state electrochemiluminescence sensor for detecting mercury ions prepared in the above-mentioned specific example 1 as the working electrode, and using the same experimental conditions as in the above-mentioned specific example 2, Hg2 ⁺ standard solutions with three concentrations of high, medium and low were detected, and the results are shown in the following table.

It can be seen from the above table that the recovery rate is between 90.8% and 97.4%, indicating that the accuracy is good. The RSD is between 6.4 and 11.0%, indicating that the precision is good.

The above description does not limit the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the essential scope of the present invention shall also belong to the protection scope of the present invention, and the protection scope of the present invention shall be determined by the claims.

Claims (6)

1. A solid-state electrochemical luminescence sensor for detecting mercury ions, characterized in that: the surface of the working electrode is solidly loaded with electropolymerized N-(4-aminobutyl)-N-ethyl isoluminol (ABEI), the N-(4-aminobutyl)-N-ethyl isoluminol is sequentially assembled with glutaraldehyde, DNA1, DNA2 combined by T-Hg ²⁺ -T mismatch and biological white. 2. The solid-state electrochemiluminescence sensor for detecting mercury ions according to claim 1, wherein the working electrode is a glassy carbon electrode. 3. a method for preparing a solid-state electrochemiluminescent sensor for detecting mercury ions according to claim 1, characterized in that the specific steps are as follows: (1) Preparation of glassy carbon electrode immobilized with DNA1 a. Polish the glassy carbon electrode with a diameter of 3-5 mm with aluminum oxide of 1.0 μm, 0.3 μm, and 0.05 μm in sequence, then ultrasonically clean it with ethanol and water in sequence, rinse it with water, and dry it with nitrogen for later use; b. Place the glassy carbon electrode obtained in step (a) in the H ₂ SO ₄ solution containing N-(4-aminobutyl)-N-ethylisoluminol (ABEI), and perform cyclic voltammetry scanning. The range is ?0.2-1.5 V, and the scanning speed is 0.01-0.1 V/s to scan 20-30 times, so that ABEI is electropolymerized on the surface of the glassy carbon electrode; the said N-(4-aminobutyl)-N -The concentration of N-(4-aminobutyl)-N-ethylisoluminol (ABEI) in H ₂ SO ₄ solution is 0.01～0.0001 mol/L, H ₂ SO ₄ The concentration is 0.1-1 mol/L; c. After washing the glassy carbon electrode obtained in step (b) with 0.01-0.1 M PBS buffer solution with pH = 7-8, add 10-20 μL of 1-3 wt% glutaraldehyde solution dropwise on the surface of the glassy carbon electrode, Stand for 20-40 minutes; d. After washing the glassy carbon electrode obtained in step (c) with 0.01-0.1 M PBS buffer solution with pH = 7-8, add 0.01 ~ 10 ~ 20 μL of 0.1 M PBS buffer solution, let stand for 20 ~ 40 min to make DNA1 bind to the electrode surface; e. Soak the glassy carbon electrode obtained in step (d) in 10-20 μL bovine serum albumin solution with a mass percent concentration of 2%, and seal it for 1-2 hours to obtain a glassy carbon electrode immobilized with DNA1; (2) Assembly of solid-state electrochemiluminescence sensor a. Prepare a series of standard solutions containing mercury ions with different concentrations, and mix the standard solution with 0.01-0.1 M PBS buffer solution containing 10 μmol/L DNA2 and pH = 7-8 at a volume ratio of 1:1; b. Take 10-20 μL of the mixed solution obtained in step (a) and drop it on the surface of the glassy carbon electrode loaded with DNA1. Buffer washing; c. Take an appropriate amount of 0.01-0.1 M PBS buffer solution with pH = 7-8 to prepare 0.01-0.1 mg/mL avidin solution, and add 10-20 μL of avidin solution dropwise to the surface of the glassy carbon electrode obtained in step (b). After incubation for 5 min; d. After the glassy carbon electrode obtained in step (c) is washed with 0.01-0.1 M PBS buffer solution with pH = 7-8, a solid-state electrochemiluminescence sensor for mercury ion detection is obtained. 4. A method for preparing a solid-state electrochemiluminescent sensor for detecting mercury ions according to claim 3, characterized in that: the structural formula of DNA1 is: 5'-NH ₂ -(CH ₂ ) ₆ - GAC T GTC T CGT T CGC T TAG-3'; the structural formula of DNA2 is: 5'-biotin-CTA T GCG T ACG T GAC T GTC-3'. 5. a detection method according to any one of claim 1-4 detecting the solid-state electrochemical luminescence sensor of mercury ion, it is characterized in that concrete steps are as follows: (1) Standard curve establishment a. after the glassy carbon electrode that is loaded with DNA1 described in claim 3 is rinsed clean with 0.01～0.1 M PBS buffer solution, in the 0.05～0.2 M carbonate buffer solution of pH=9～10, start electrochemical Reaction, test electrochemiluminescence intensity I ₀ ; b. the solid-state electrochemiluminescence sensor for mercury ion detection described in claim 3 is put into 0.05～0.2 M carbonate buffer solution of pH=9～10, starts electrochemical reaction, measures electrochemiluminescence intensity, obtains The electrochemiluminescence intensity value I ₁ corresponding to a series of different concentrations of Hg ²⁺ solutions, calculate the change value of the electrochemiluminescence intensity of a series of different concentrations of Hg ²⁺ solutions ΔI= I ₀ ?I ₁ , and establish the value of the electrochemiluminescence intensity Change the quantitative relationship between the value ΔI and the concentration of the Hg ²⁺ solution; (2) Determination of samples to be tested a. Mix the sample solution to be tested containing mercury ions with 0.01-0.1 M PBS buffer solution of pH 7-8 containing 10 μmol/L DNA2 at a volume ratio of 1:1; b. Take 10-20 μL of the mixed solution obtained in step (a) and drop it on the surface of the glassy carbon electrode loaded with DNA1. Buffer washing; c. Add 10-20 μL of 0.01-0.1 mg/mL avidin solution prepared in 0.01-0.1 M PBS buffer solution with pH = 7-8 to the surface of the glassy carbon electrode obtained in step (b), and incubate for 5 min; d. After cleaning the glassy carbon electrode obtained in step (c) with 0.01-0.1 M PBS buffer solution with pH = 7-8, it is used as a working electrode, a saturated calomel electrode or an Ag/AgCl electrode is used as a reference electrode, and a platinum wire electrode is used as a counter electrode. Electrode, build a three-electrode system, put it into 0.05-0.2 M carbonate buffer solution with pH = 9-10, start the electrochemical reaction, test the value of the intensity of electrochemiluminescence, according to the change value of the intensity of electrochemiluminescence ΔI and Hg ^{2 +} The quantitative relationship between the concentration of the solution is calculated to obtain the accurate concentration C _Hg of Hg ²⁺ in the sample solution to be tested. 6. the detection method of a kind of solid-state electrochemiluminescence sensor that detects mercury ion according to claim 5 is characterized in that: the hydrogen peroxide that contains 1 mM in the described carbonate buffer solution, the electrochemical method that adopts Potential step chronoamperometry; potential step: 0 V step to 1 V; pulse width: 0.25 s; measurement time interval: 30 s.