Ag (at) SiO2 (at) mSiO2 (at) luminol composite material, preparation method, unmarked electrochemical luminescence sensor and application

Abstract

The invention provides an Ag (at) SiO2 (at) mSiO2 (at) luminol composite material, a preparation method, an unmarked electrochemical luminescence sensor and application, and relates to the technical field of metal ion detection. The Ag (at) SiO2 (at) mSiO2 (at) luminol nano composite material has a core-shell structure, the core-shell structure sequentially comprises silver nanoparticles, a silicon dioxide layer, a mesoporous silicon dioxide layer and luminol molecules from inside to outside, and the luminol molecules are embedded into mesopores of the mesoporous silicon dioxide layer. The label-free electrochemical luminescence sensor constructed based on the material realizes rapid, low-cost and ultra-sensitive detection of Hg < 2 + >.

Description

Technical Field

[0001] This invention relates to the field of metal ion detection technology, specifically to an Ag@SiO2@mSiO2@luminol composite material and its preparation method, a label-free electrochemiluminescence sensor and its application. Background Technology

[0002] Chinese medicinal herbs are susceptible to the absorption of heavy metals such as mercury (Hg) due to environmental factors, processing, and storage conditions. 2+ Hg contamination poses a serious threat to human health. However, existing detection technologies typically suffer from high instrument costs, low sensitivity, and insufficient anti-interference capabilities. This project aims to prepare a novel, highly efficient electrochemiluminescence (ECL) nanomaterial by leveraging the synergistic enhancement effect of surface plasmon resonance and nanoconfining. This material can be used to construct analytical interfaces to detect Hg in traditional Chinese medicine. 2+ Rapid, low-cost, and highly sensitive detection. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides an Ag@SiO2@mSiO2@luminol composite material and its preparation method, as well as a label-free electrochemiluminescence sensor and its application, which solves the problems of high instrument cost, low sensitivity, and insufficient anti-interference ability that existing detection technologies typically suffer from.

[0005] (II) Technical Solution

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides an Ag@SiO2@mSiO2@luminol nanocomposite material, wherein the Ag@SiO2@mSiO2@luminol nanocomposite material has a core-shell structure, wherein the core-shell structure comprises, from the inside out, silver nanoparticles, a silica layer, a mesoporous silica layer, and luminol molecules, wherein the luminol molecules are embedded in the mesopores of the mesoporous silica layer.

[0008] Preferably, the particle size D50 of the Ag@SiO2@mSiO2@luminol nanocomposite is 100-140 nm.

[0009] Preferably, the thickness of the silicon dioxide layer is 2-4 nm, the thickness of the mesoporous silicon dioxide layer is 28-30 nm, and the pore size of the mesoporous silicon dioxide layer is 2-4 nm.

[0010] In a second aspect, the present invention provides a method for preparing Ag@SiO2@mSiO2@luminol nanocomposite materials as described in the first aspect, comprising the following steps:

[0011] S1, Synthesis of Silver Nanoparticles

[0012] Polyvinylpyrrolidone was dissolved in ethylene glycol, and then silver nitrate was added. The mixture was stirred and reacted at 120-140℃ for 50-70 minutes. Acetone was added to the reaction system and the silver nanoparticle precipitate was separated. The silver nanoparticle precipitate was dispersed in anhydrous ethanol to obtain a silver nanoparticle colloidal solution with a concentration of 0.04-0.06 g / mL.

[0013] Synthesis of S2 and Ag@SiO2

[0014] Ethanol, water and ammonia solution are mixed to obtain a first mixture. Tetraethyl silicate is dissolved in ethanol to obtain a first tetraethyl silicate solution. The silver nanoparticle colloidal solution is dispersed in the first mixture. The first tetraethyl silicate solution is then added dropwise to the first mixture. The reaction is carried out for 5-7 hours to obtain Ag@SiO2 particles.

[0015] Synthesis of S3 and Ag@SiO2@mSiO2

[0016] A second mixture is obtained by mixing water, ethanol, hexadecyltrimethylammonium bromide (CTAB), and ammonia solution. Tetraethyl silicate is dissolved in ethanol to obtain a second tetraethyl silicate solution. The Ag@SiO2 particles are added to the second mixture and mixed evenly. Then, the second tetraethyl silicate solution is slowly added and reacted for 30-50 minutes. Methyltrimethoxysilane is then added and reacted for 4-6 hours to obtain the reaction product. Methanol and concentrated hydrochloric acid are mixed to obtain a third mixture. The reaction product is dispersed in the third mixture and refluxed at 70-90°C for 20-30 hours. After centrifugation, washing, and drying with ethanol, Ag@SiO2@mSiO2 is obtained.

[0017] Synthesis of S4, Ag@SiO2@mSiO2@luminol

[0018] A luminol solution was prepared by dissolving luminol in DMSO. The luminol solution and water were added to the Ag@SiO2@mSiO2 mixture, and the mixture was dispersed and reacted for 10-14 hours. The precipitate was then collected by filtration. The precipitate was the Ag@SiO2@mSiO2@luminol composite material.

[0019] Luminol is an electrochemiluminescent material with pKa values ​​of 6.74 and 15.1. The optimal fluorescence wavelength of Luminol is 425 nm. CAS No.: 521-31-3.

[0020] Preferably, in step S2, the volume ratio of the silver nanoparticle colloidal solution to the first tetraethyl silicate solution is 400:3.

[0021] Preferably, in step S3, the volume ratio of Ag@SiO2 particles to tetraethyl orthosilicate solution is 25:1.

[0022] Preferably, in step S3, the mass-to-volume ratio of the reaction product to the third mixture is 1:4.

[0023] Thirdly, the present invention provides a label-free electrochemiluminescence sensor, the label-free electrochemiluminescence sensor including a signal conversion and amplification element, the signal conversion and amplification element including the Ag@SiO2@mSiO2@luminol nanocomposite material described in the first aspect.

[0024] Preferably, the label-free electrochemiluminescence sensor specifically recognizes mercury ions, and the linear detection range for mercury ions is 1×10⁻⁶. -10 ~1×10 -15 g / mL.

[0025] Fourthly, the present invention provides an application of the label-free electrochemiluminescence sensor described in the third aspect in detecting the mercury ion content in traditional Chinese medicine materials, wherein the spiked recovery rate of the label-free electrochemiluminescence sensor is 96% to 103%.

[0026] (III) Beneficial Effects

[0027] This invention provides an Ag@SiO2@mSiO2@luminol composite material and its preparation method, a label-free electrochemiluminescence sensor, and its application. Compared with the prior art, it has the following advantages:

[0028] This invention provides an Ag@SiO2@mSiO2@luminol nanocomposite material with a core-shell structure. The core-shell structure, from the inside out, comprises silver nanoparticles, a silica layer, a mesoporous silica layer, and luminol molecules, with the luminol molecules embedded in the mesopores of the mesoporous silica layer. This core-shell structured Ag@SiO2@mSiO2@luminol nanomaterial exhibits excellent electrochemiluminescence (ECL) properties thanks to the synergistic enhancement effect of the surface plasmon resonance effect of AgNPs and the nanoconfinement effect of mesoporous silica (mSiO2). A label-free electrochemiluminescence sensor based on this material enables the detection of Hg... 2+This sensor offers rapid, low-cost, and ultra-sensitive detection. Furthermore, it demonstrated excellent anti-interference capabilities and accuracy in actual traditional Chinese medicine sample testing, indicating its significant application potential in the quality control of medicinal materials and the monitoring of heavy metal pollution. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A schematic diagram of the process of constructing a label-free electrochemiluminescence sensor based on Ag@SiO2@mSiO2@luminol nanomaterials prepared in Example 1;

[0031] Figure 2 These are the electrochemiluminescence values ​​corresponding to the blank group and mercuric nitrate solutions of different concentrations;

[0032] Figure 3 It is ΔI and Hg 2+ The linear relationship between the logarithms of concentrations;

[0033] Figure 4 The label-free electrochemiluminescence sensor prepared in Example 1 is for Hg 2+ Specific experimental results;

[0034] Figure 5 The cyclic voltammetry (A) curves and corresponding I values ​​for AgNPs, Ag@SiO2, Ag@SiO2@mSiO2, and Ag@SiO2@mSiO2@luminol are shown. ECL -E curve (B);

[0035] Figure 6 This is the electrochemical impedance spectroscopy (EIP) diagram of the label-free electrochemiluminescence sensor prepared in Example 1.

[0036] Among them, a—Ag@SiO2@mSiO2@luminol / T-COOH / FTO modified electrode, b—Ag@SiO2@mSiO2@luminol / T-Hg 2+ -T / FTO modified electrode;

[0037] Figure 7 This is a transmission electron microscope (TEM) image of the Ag@SiO2@mSiO2 material prepared in Example 1. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] This application provides an Ag@SiO2@mSiO2@luminol composite material and its preparation method, a label-free electrochemiluminescence sensor and its application, which solves the problems of high instrument cost, low sensitivity and insufficient anti-interference ability of existing detection technologies, and realizes the detection of Hg in traditional Chinese medicine. 2+ Rapid, low-cost, and highly sensitive detection.

[0040] The technical solution in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0041] 1. The Ag@SiO2@mSiO2@luminol nanocomposite material disclosed in this invention has a core-shell structure, wherein the core-shell structure comprises silver nanoparticles, a silica layer, a mesoporous silica layer, and luminol molecules from the inside out, and the luminol molecules are embedded in the mesopores of the mesoporous silica layer. Because the Ag@SiO2@mSiO2@luminol composite material has silanol groups on its surface, it can bind to the ethoxy groups (-OC2H5) in the 3-aminopropyltriethoxysilane (APTES) molecule. After the reaction, the amino groups in APTES bind to the surface of Ag@SiO2@mSiO2@luminol nanoparticles, completing the amination of the Ag@SiO2@mSiO2@luminol composite material. Then, N-hydroxysuccinimide (NHS) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) are used to activate the carboxyl groups of T-COOH, causing them to react with the amino groups of the amination-treated Ag@SiO2@mSiO2@luminol nanomaterials to form stable amide bonds. During the detection process, Hg is added... 2+ After that, Hg 2+ It can form a stable coordinate bond with the N3 site of two thymine (T) bases, constituting T-Hg. 2+ The -T linear complex reduces electrode impedance and promotes electron transfer on the electrode, thereby enhancing electrochemiluminescence.

[0042] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0043] I. Preparation Method

[0044] Example 1

[0045] This embodiment provides a method for preparing Ag@SiO2@mSiO2@luminol nanocomposite materials, including the following steps:

[0046] (1) Synthesis of AgNPs

[0047] 2.5 g of polyvinylpyrrolidone (PVP) (Mw=58000) was dissolved in a 200 mL ethylene glycol flask, and 0.5 g of silver nitrate (AgNO3) was added. The reaction mixture was transferred to an oil bath heating device, and the temperature was increased to 130 °C over 25 minutes with continuous vigorous stirring. This reaction temperature was maintained for 60 minutes to ensure the complete formation of AgNPs. Subsequently, 800 mL of acetone was added to the reaction system to precipitate and separate AgNPs by solvent displacement. The precipitate was collected by centrifugation at 10000 rpm for 3 minutes. Finally, the obtained AgNPs were redispersed in 4 mL of anhydrous ethanol to prepare a colloidal solution with a concentration of 0.05 g / mL.

[0048] (2) Synthesis of Ag@SiO2

[0049] After dispersing the synthesized AgNPs colloidal solution under ultrasonic conditions for 20 min, 2 mL of AgNPs colloidal solution (0.05 g / mL) was dispersed in a mixture of ethanol (50 mL), water (20 mL), and 1 mL of ammonia solution (28 wt%). Then, 15 μL of tetraethyl silicate was added to 30 mL of ethanol, and after mixing thoroughly, the tetraethyl silicate solution was slowly added dropwise to the mixture under continuous stirring. The reaction was allowed to proceed for 6 hours. After centrifugation and washing several times with ethanol and water, Ag@SiO2 particles were obtained.

[0050] (3) Synthesis of Ag@SiO2@mSiO2

[0051] 80 μL of tetraethyl silicate was dissolved in 1.5 mL of ethanol to obtain a tetraethyl silicate solution. A blend was prepared by mixing 25 mL of water, 15 mL of ethanol, 75 mg of CTAB, and 0.25 mL of ammonia (28 wt%). Ag@SiO2 particles were added to the blend and dispersed evenly after ultrasonic and mechanical stirring for 30 minutes each. Subsequently, 0.5 mL of tetraethyl silicate solution was slowly added every 10 minutes under continuous rapid stirring. After 40 minutes, 18 μL of methyltrimethoxysilane diluted with 1 mL of ethanol was added to modify the surface of the Ag@SiO2@mSiO2 material that had not yet had its mesoporous structure removed, forming hydrophobic silicon. The reaction was carried out for 6 hours. The surface-modified Ag@SiO2@mSiO2 was obtained by centrifugation and washing with ethanol and water, respectively, and dispersed in 2 mL of ethanol. Ag@SiO2@mSiO2 solution was dispersed in a mixture of 15 mL methanol and 1 mL concentrated HCl, and refluxed at 80 °C for 24 hours to remove CTAB, forming a material containing mesoporous silica. This material was then washed six times by centrifugation with ethanol at 6000 rpm and dried to obtain Ag@SiO2@mSiO2. A transmission electron microscope (TEM) image of the Ag@SiO2@mSiO2 material is shown below. Figure 7 ,Depend on Figure 7 It can be seen that the Ag@SiO2@mSiO2 material has a good core-shell structure, and its mSiO2 thickness is about 29.37 nm.

[0052] (4) Synthesis of Ag@SiO2@mSiO2@luminol

[0053] Prepare a 0.5 mg / mL luminol / DMSO solution. Weigh 1 mg of Ag@SiO2@mSiO2, add 20 μL of luminol / DMSO solution and 1 mL of water, sonicate to disperse, stir for 12 h, transfer to a centrifuge tube, centrifuge at 6000 rpm for 5 min, and then wash once with ethanol and water by centrifugation to obtain Ag@SiO2@mSiO2@luminol composite material with a particle size D50 of 120 nm.

[0054] Label-free electrochemiluminescence sensors were fabricated from the Ag@SiO2@mSiO2@luminol composite material prepared above, such as... Figure 1 As shown, the specific steps include the following:

[0055] S1. Amino-functionalization of Ag@SiO2@mSiO2@luminol nanocomposites

[0056] Weigh 6 mg of Ag@SiO2@mSiO2@luminol composite material and add 3 mL of ethanol. After dispersing evenly, add 100 μL of 3-aminopropyltriethoxysilane (APTES). Stir at room temperature for 1 hour, and then wash with ethanol and water by centrifugation to obtain aminated Ag@SiO2@mSiO2@luminol nanocomposite material.

[0057] S2. Combining aminated Ag@SiO2@mSiO2@luminol nanomaterials with thymine-1-acetic acid (T-COOH)

[0058] 2 mM of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and 2 mM of N-hydroxythiosuccinimide sodium salt (NHS) were dissolved in PBS buffer containing 0.5 M NaCl at pH 6.0. Then, 2 mL of 1 mM T-COOH aqueous solution was added to the solution. After reacting at room temperature for 30 min, carboxyl-activated T-COOH was obtained.

[0059] 6 mL of aminated Ag@SiO2@mSiO2@luminol (after centrifugation and washing with water, the material was dispersed in water; therefore, the aminated Ag@SiO2@mSiO2@luminol was a 1 mg / mL dispersion at this point) was added dropwise to 3 mL of carboxyl-activated T-COOH while stirring. After stirring at room temperature for 4 h, the mixture was centrifuged and washed with water to obtain a T-COOH-modified Ag@SiO2@mSiO2@luminol nanomaterial solution.

[0060] S3. Add 20 μL of a solution of Ag@SiO2@mSiO2@luminol nanomaterials modified with L-COOH to the cleaned electrode surface and incubate at 40℃ for 2 h to obtain the modified electrode, i.e., label-free electrochemiluminescence Hg. 2+ sensor.

[0061] Example 2

[0062] This embodiment provides a method for preparing Ag@SiO2@mSiO2@luminol nanocomposite materials, including the following steps:

[0063] (1) Synthesis of silver nanoparticles (AgNPs)

[0064] 2.5 g of polyvinylpyrrolidone (PVP) (Mw=58000) was dissolved in a 200 mL ethylene glycol flask, and 0.5 g of silver nitrate (AgNO3) was added. The reaction mixture was transferred to an oil bath heating device, and the temperature was increased to 120 °C over 25 minutes with continuous vigorous stirring. This temperature was maintained for 70 minutes. Subsequently, 800 mL of acetone was added to the reaction system to obtain AgNPs precipitate. The precipitate was collected by centrifugation at 10000 rpm for 3 minutes. Finally, the obtained AgNPs were redispersed in 4 mL of anhydrous ethanol to prepare an AgNPs colloidal solution with a concentration of 0.05 g / mL.

[0065] (2) Synthesis of Ag@SiO2

[0066] After dispersing the synthesized AgNPs colloidal solution under ultrasonic conditions for 20 min, 2 mL of AgNPs colloidal solution (0.05 g / mL) was dispersed in a mixture of ethanol (50 mL), water (20 mL), and 1 mL of ammonia solution (28 wt%). Then, 15 μL of tetraethyl silicate was added to 30 mL of ethanol, and after mixing thoroughly, the tetraethyl silicate solution was slowly added dropwise to the mixture under continuous stirring. The reaction was allowed to proceed for 5 hours. After centrifugation and washing several times with ethanol and water, Ag@SiO2 particles were obtained.

[0067] (3) Synthesis of Ag@SiO2@mSiO2

[0068] 80 μL of tetraethyl silicate was dissolved in 1.5 mL of ethanol to obtain a tetraethyl silicate solution. A blend was prepared by mixing 25 mL of water, 15 mL of ethanol, 75 mg of CTAB and 0.25 mL of ammonia (28 wt%). Ag@SiO2 particles were added to the blend and dispersed evenly after ultrasonic and mechanical stirring for 50 minutes each. Then, 0.5 mL of tetraethyl silicate solution was slowly added every 10 minutes under continuous rapid stirring. After 40 min, 18 μL of methyltrimethoxysilane diluted with 1 mL of ethanol was added to modify the surface of Ag@SiO2@mSiO2 material that still had CTAB removed, forming hydrophobic mesoporous silica. The reaction was carried out for 4 hours, and the particles were collected by centrifugation. The particles were washed with ethanol and water respectively to obtain surface-modified particles. The surface-modified particles were dispersed in a mixture of 15 mL of methanol and 1 mL of concentrated HCl and refluxed at 80 °C for 24 h to remove CTAB, forming a material containing mesoporous silica. The material was then washed six times by centrifugation with ethanol at 6000 rpm and dried to obtain Ag@SiO2@mSiO2.

[0069] (4) Synthesis of Ag@SiO2@mSiO2@luminol

[0070] Prepare a 0.5 mg / mL luminol / DMSO solution. Weigh 1 mg of Ag@SiO2@mSiO2, add 20 μL of luminol / DMSO solution and 1 mL of water, sonicate to disperse, stir for 14 h, transfer to a centrifuge tube, centrifuge at 6000 rpm for 5 min, and then wash once with ethanol and water by centrifugation to obtain the Ag@SiO2@mSiO2@luminol composite material.

[0071] A label-free electrochemiluminescence sensor was prepared from the Ag@SiO2@mSiO2@luminol composite material as described above, using the same method as in Example 1.

[0072] Example 3

[0073] This embodiment provides a method for preparing Ag@SiO2@mSiO2@luminol nanocomposite materials, including the following steps:

[0074] (1) Synthesis of AgNPs

[0075] 2.5 g of polyvinylpyrrolidone (PVP) (Mw=58000) was dissolved in a 200 mL ethylene glycol flask, and 0.5 g of silver nitrate (AgNO3) was added. The reaction mixture was transferred to an oil bath heating apparatus, and the temperature was increased to 140 °C over 25 minutes with continuous vigorous stirring. This reaction temperature was maintained for 50 minutes to ensure the complete formation of AgNPs. Subsequently, 800 mL of acetone was added to the reaction system to precipitate and separate AgNPs by solvent displacement. The precipitate was collected by centrifugation at 10000 rpm for 3 minutes. Finally, the obtained AgNPs were redispersed in 4 mL of anhydrous ethanol to prepare a colloidal solution with a concentration of 0.05 g / mL.

[0076] (2) Synthesis of Ag@SiO2

[0077] After dispersing the synthesized AgNPs colloidal solution under ultrasonic conditions for 20 min, 2 mL of AgNPs colloidal solution (0.05 g / mL) was dispersed in a mixture of ethanol (50 mL), water (20 mL), and 1 mL of ammonia solution (28 wt%). Then, 15 μL of tetraethyl silicate was added to 30 mL of ethanol, and after mixing thoroughly, the tetraethyl silicate solution was slowly added dropwise to the mixture under continuous stirring. The reaction was allowed to proceed for 7 hours. After centrifugation and washing several times with ethanol and water, Ag@SiO2 particles were obtained.

[0078] (3) Synthesis of Ag@SiO2@mSiO2

[0079] 80 μL of tetraethyl silicate was dissolved in 1.5 mL of ethanol to obtain a tetraethyl silicate solution. A blend was prepared by mixing 25 mL of water, 15 mL of ethanol, 75 mg of CTAB and 0.25 mL of ammonia (28 wt%). Ag@SiO2 particles were added to the blend and dispersed evenly after ultrasonic and mechanical stirring for 30 minutes each. Then, 0.5 mL of tetraethyl silicate solution was slowly added every 10 minutes under continuous rapid stirring. After 40 min, 18 μL of methyltrimethoxysilane diluted with 1 mL of ethanol was added to modify the surface of the Ag@SiO2@mSiO2 material that still had mesoporous structure, forming hydrophobic mesoporous silica. The reaction was carried out for 4 hours, followed by centrifugation and washing to obtain a solution of Ag@SiO2@mSiO2. The particles were collected and washed with ethanol and water respectively to obtain surface-modified particles. The surface-modified particles were dispersed in a mixture of 15 mL of methanol and 1 mL of concentrated HCl and refluxed at 80 °C for 24 hours to remove CTAB, forming a material containing mesoporous silica. The material was then washed six times by centrifugation with ethanol at 6000 rpm and dried to obtain Ag@SiO2@mSiO2.

[0080] (4) Synthesis of Ag@SiO2@mSiO2@luminol

[0081] Prepare a 0.5 mg / mL luminol / DMSO solution. Weigh 1 mg of Ag@SiO2@mSiO2, add 20 μL of luminol / DMSO solution and 1 mL of water, sonicate to disperse, stir for 10 h, transfer to a centrifuge tube, centrifuge at 6000 rpm for 5 min, and then wash once with ethanol and water by centrifugation to obtain the Ag@SiO2@mSiO2@luminol composite material.

[0082] The above-prepared Ag@SiO2@mSiO2@luminol composite material was used to prepare a label-free electrochemiluminescence sensor, using the same method as in Example 1.

[0083] Detection example

[0084] 1. The label-free electrochemiluminescence sensor prepared in Example 1 for Hg 2+ Concentration analysis performance.

[0085] This study employed a self-made apparatus consisting of a CHI760E electrochemical workstation (Shanghai Chenhua), an RFL-1 chemiluminescence analyzer (Xi'an Ruimai), and a computer for ECL detection. A three-electrode system was used for electrochemiluminescence detection, with the working electrode being fluorine-doped tin oxide (FTO), the counter electrode being a highly stable platinum wire, and the reference electrode being a standard Ag / AgCl electrode. Prior to the experiment, the FTO electrode underwent rigorous pretreatment: sequential ultrasonic cleaning with acetone, ethanol, and ultrapure water, each lasting 10 minutes. To ensure the consistency of the conductive area on the electrode surface, holes of a specific diameter were fabricated on polyimide double-sided tape using a precision punch, and then tightly adhered to the conductive surface of the FTO electrode, thus obtaining an electrode substrate with a precise conductive area. Subsequently, the sample solution was dropped onto a defined area on the FTO electrode surface and dried in a 40°C incubator. Finally, the ECL signal of the nanomaterial-modified FTO electrode was detected and analyzed. The details are as follows.

[0086] First, accurately weigh Hg(NO3)2·H2O and prepare solutions with ultrapure water to a concentration of 1×10⁻⁶. -4 A mercuric nitrate solution of g / mL was diluted with ultrapure water to obtain concentrations of 1×10 g / mL. -10 g / mL, 1×10 -11 g / mL, 1×10 -12 g / mL, 1×10 -13 g / mL, 1×10 -14 g / mL, 1×10 -15 A 1000 g / mL mercuric nitrate solution was prepared. 50 μL of different concentrations of mercuric nitrate solution were dropped onto the surfaces of different modified electrodes. After incubation at 40℃ for 30 min, the electrode surfaces were rinsed with ultrapure water to remove unbound mercury ions. The working solution was 0.1 M PBS buffer (pH 11) containing 2 mM H₂O₂. Electrochemical detection conditions were: -700 V, 200 T / s, amplification level 3, and scan potential 0–1.5–0 V. The electrochemiluminescence values ​​corresponding to different concentrations of mercuric nitrate solution were measured. A blank control group was set up, in which ultrapure water was added to the modified electrode surface instead of mercuric nitrate solution. Electrochemiluminescence values ​​were obtained under the same test conditions. The electrochemiluminescence values ​​corresponding to different concentrations of mercuric nitrate solution and the blank control group are shown in [reference needed]. Figure 2 .

[0087] Depend on Figure 2 It can be seen that the electrochemiluminescence value of the blank group is lower than that of the mercuric nitrate solution. This is because the addition of Hg... 2+ After that, Hg 2+It can form a stable coordinate bond with the N3 site of two thymine (T) bases, constituting T-Hg. 2+ -T linear complex, characterized by electrochemical impedance spectroscopy ( Figure 6 The formation of this complex reduces electrode impedance and promotes electron transfer at the electrode, as the Hg in the mercuric nitrate solution... 2+ As the concentration increases, the electrode impedance decreases continuously, and therefore, the intensity of the electrochemiluminescence signal gradually increases.

[0088] The electrochemiluminescence values ​​corresponding to different concentrations of mercuric nitrate solutions are denoted as I, and the electrochemiluminescence value of the blank control group is denoted as I0. The difference between I and I0 is denoted as ΔI (ΔI = I - I0). The difference ΔI is plotted as the ordinate, and Hg is used as the plotting factor. 2+ A standard curve was plotted with the logarithm of concentration on the x-axis. This standard curve is shown in [reference needed]. Figure 3 .

[0089] like Figure 3 ΔI and Hg 2+ The logarithm of the concentration shows a linear relationship, at 1×10 -10 g / mL~1×10 -15 Within the concentration range of g / mL (0.29 nM to 2.9 fM), the electrochemiluminescence signal of the sensor changes with Hg. 2+ The effect is enhanced with increasing concentration. The linear regression equation is ΔI = 596.502 × logC + 9359.39 (C in g / mL), and the linear correlation coefficient R0 is [value missing]. 2 =0.998. With a signal-to-noise ratio of 3, the detection limit of the sensor prepared in Example 1 is 3.54 × 10⁻⁶. -16 g / mL, for Hg 2+ It exhibits excellent performance in concentration analysis.

[0090] The label-free electrochemiluminescence sensor prepared in Example 1 is compared with existing Hg based on electrochemiluminescence technology. 2+ A systematic comparative analysis of the detection methods was conducted, and the results are shown in Table 1. As shown in Table 1, the detection limit of the label-free electrochemiluminescence sensor prepared in Example 1 is higher than that of the previously reported Hg detection method. 2+ The sensor is at least an order of magnitude lower.

[0091] Table 1. Example 1: Label-free electrochemiluminescence sensor and other Hg detection methods. 2+ Comparison of electrochemiluminescence methods

[0092]

[0093] 2. Label-free electrochemiluminescence sensor for Hg in Example 1 2+ Specificity

[0094] Select Pb 2+Cd 2+ Cu 2+ Al 3+ Cr 3+ Fe 3+ Ba 2+ Na + Ca 2+ Mg 2+ Metal ions were used as interfering agents in the interference experiment. The concentration of the interfering agent was higher than that of Hg. 2+ 10 times higher, Pb 2+ Cd 2+ Cu 2+ Al 3+ Cr 3+ Fe 3+ Ba 2+ Na + Ca 2+ Mg 2+ The concentration was 0.029 nM, and the test results were as follows: Figure 4 .Depend on Figure 4 As shown, only when Hg exists 2+ The sensor only produces a strong ΔI value under specific conditions; the ΔI value is weaker in the presence of other interfering metal ions. Therefore, the label-free electrochemiluminescence sensor prepared in Example 1 can specifically detect Hg. 2+ .

[0095] 3. Accuracy of the label-free electrochemiluminescence sensor prepared in Example 1

[0096] To verify the accuracy and practicality of the label-free electrochemiluminescence sensor constructed in Example 1, this sensor was used to detect Hg in Panax notoginseng. 2+ The concentration was determined. Before testing, the Panax notoginseng stock solution was diluted 10,000 times with ultrapure water. Spiked concentrations were 0.01, 0.1, and 1 pg / mL, and the results are as follows: Figure 5 .Depend on Figure 5 The recovery rates in this experiment ranged from 96.6% to 103.0%, indicating that the complex matrix in the actual samples did not significantly affect the label-free electrochemiluminescence sensor's detection of Hg. 2+ Quantitative detection proves that the sensor has good accuracy and practical application potential.

[0097] Preparation method of Panax notoginseng stock solution: Accurately weigh 0.2g of Panax notoginseng powder and place it in a polytetrafluoroethylene digestion vessel. Add 6mL of nitric acid and 2mL of hydrogen peroxide sequentially, seal, and soak overnight at room temperature for pre-digestion. The next day, place the digestion vessel on a heating plate and use a gradient temperature program: first, raise the temperature from room temperature to 120℃ and maintain it for 1 hour, then raise the temperature to 140℃ and continue digestion for 8 hours until the sample is completely dissolved. After digestion, perform acid removal treatment. Stop heating when the solution is concentrated to 2mL and cool to room temperature. Quantitatively transfer the digestion solution to a 50mL volumetric flask, wash the digestion vessel several times with deionized water, combine the washings, and dilute to the mark. Mix thoroughly to obtain the stock solution.

[0098] Test case

[0099] According to the heavy metal limits specified in the Chinese Pharmacopoeia for 28 kinds of Chinese medicinal materials and their processed products, three representative medicinal materials—Panax notoginseng, Salvia miltiorrhiza, and Crataegus pinnatifida—were selected as actual samples. The label-free electrochemiluminescence sensor prepared in Example 1 was used to measure Hg. 2+ Content detection. Stock solutions of Panax notoginseng, Salvia miltiorrhiza, and Crataegus pinnatifida were prepared according to the above-described method for preparing Panax notoginseng stock solution. To verify the reliability of the label-free electrochemiluminescence sensor constructed in Example 1, parallel detection of the extracts of the three herbs was performed using both ICP-MS and the present sensor. The results are shown in Table 2. As shown in Table 2, the relative standard deviation (RSD) of the results determined by the two methods was 3.33%–11.51%, indicating that the detection data of the present sensor has good consistency with the standard ICP-MS method. According to the pharmacopoeia, the Hg content in the above-mentioned herbs is... 2+ The limit for Hg is 0.2 mg / kg. Test results showed that the Hg levels in the three medicinal herbs were... 2+ The contents were all significantly lower than the limit value, meeting the pharmacopoeia requirements. This result not only confirms the detection reliability of the developed sensor, but also indicates that the selected medicinal material samples have a low risk of heavy metal contamination.

[0100] Table 2 shows the results of parallel testing of the extracts from the three medicinal herbs using different methods.

[0101]

[0102] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0103] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0104] The present invention has been illustrated with the above embodiments to describe the detailed process flow of the present invention. However, the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An Ag@SiO2@mSiO2@luminol nanocomposite material, characterized in that, The Ag@SiO2@mSiO2@luminol nanocomposite material has a core-shell structure, which includes silver nanoparticles, a silica layer, a mesoporous silica layer, and luminol molecules from the inside out. The luminol molecules are embedded in the mesopores of the mesoporous silica layer.

2. The Ag@SiO2@mSiO2@luminol nanocomposite material as described in claim 1, characterized in that, The Ag@SiO2@mSiO2@luminol nanocomposite has a particle size D50 of 100-140 nm.

3. The Ag@SiO2@mSiO2@luminol nanocomposite material as described in claim 1, characterized in that, The thickness of the silicon dioxide layer is 2-4 nm, the thickness of the mesoporous silicon dioxide layer is 28-30 nm, and the pore size of the mesoporous silicon dioxide layer is 2-4 nm.

4. A method for preparing Ag@SiO2@mSiO2@luminol nanocomposite material as described in any one of claims 1-3, characterized in that, Includes the following steps: S1, Synthesis of Silver Nanoparticles Polyvinylpyrrolidone was dissolved in ethylene glycol, and then silver nitrate was added. The mixture was stirred and reacted at 120-140℃ for 50-70 minutes. Acetone was added to the reaction system and the silver nanoparticle precipitate was separated. The silver nanoparticle precipitate was dispersed in anhydrous ethanol to obtain a silver nanoparticle colloidal solution with a concentration of 0.04-0.06 g / mL. Synthesis of S2 and Ag@SiO2 Ethanol, water and ammonia solution are mixed to obtain a first mixture. Tetraethyl silicate is dissolved in ethanol to obtain a first tetraethyl silicate solution. The silver nanoparticle colloidal solution is dispersed in the first mixture. The first tetraethyl silicate solution is then added dropwise to the first mixture. The reaction is carried out for 5-7 hours to obtain Ag@SiO2 particles. Synthesis of S3 and Ag@SiO2@mSiO2 A second mixture is obtained by mixing water, ethanol, hexadecyltrimethylammonium bromide, and ammonia solution. Tetraethyl silicate is dissolved in ethanol to obtain a second tetraethyl silicate solution. The Ag@SiO2 particles are added to the second mixture and mixed evenly. Then, the second tetraethyl silicate solution is slowly added and reacted for 30-50 minutes. Methyltrimethoxysilane is then added and reacted for 4-6 hours to obtain the reaction product. Methanol and concentrated hydrochloric acid are mixed to obtain a third mixture. The reaction product is dispersed in the third mixture and refluxed at 70-90°C for 20-30 hours. After centrifugation, washing, and drying with ethanol, Ag@SiO2@mSiO2 is obtained. Synthesis of S4, Ag@SiO2@mSiO2@luminol A luminol solution was prepared by dissolving luminol in dimethyl sulfoxide. The luminol solution and water were added to the Ag@SiO2@mSiO2 and the mixture was dispersed and reacted for 10-14 hours. The precipitate was then collected by filtration. The precipitate was the Ag@SiO2@mSiO2@luminol composite material.

5. The preparation method of Ag@SiO2@mSiO2@luminol nanocomposite material as described in claim 4, characterized in that, In S2, the volume ratio of the silver nanoparticle colloidal solution to the first tetraethyl silicate solution is 400:

3.

6. The preparation method of Ag@SiO2@mSiO2@luminol nanocomposite material as described in claim 4, characterized in that, In S3, the volume ratio of Ag@SiO2 particles to tetraethyl orthosilicate solution is 25:

1.

7. The preparation method of Ag@SiO2@mSiO2@luminol nanocomposite material as described in claim 4, characterized in that, In S3, the mass-to-volume ratio of the reaction product to the third mixture is 1:

4.

8. A label-free electrochemiluminescence sensor, characterized in that, The label-free electrochemiluminescence sensor includes a signal conversion and amplification element, which includes the Ag@SiO2@mSiO2@luminol nanocomposite material as described in any one of claims 1-7.

9. The label-free electrochemiluminescence sensor as described in claim 8, characterized in that, The label-free electrochemiluminescence sensor specifically recognizes mercury ions, with a linear detection range of 1×10⁻⁶. -10 ~1×10 -15 g / mL.

10. The application of the label-free electrochemiluminescence sensor according to claim 8 or 9 in detecting mercury ion content in traditional Chinese medicine, characterized in that, The spiked recoveries of the label-free electrochemiluminescence sensor ranged from 96% to 103%.

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