Gold nanocluster electrogenerated chemiluminescence probe and preparation method thereof

Abstract

The invention discloses a gold nanocluster electrogenerated chemiluminescence probe which is a multifunctional gold nanocluster obtained by taking a 2-sulfydryl-1, 3, 4-thiadiazole ligand as a reducing agent or a protective agent. Comprising a solid-phase probe with a gold cluster modified on an electrode; or the gold cluster is independent of the electrode and is a liquid-phase probe dissolved in the electrolyte during use. The obtained electrogenerated chemiluminescence gold nanocluster probe can generate an electrogenerated chemiluminescence signal under the condition of no co-reactant, and is relatively low in luminescence potential, high in quantum yield and good in biocompatibility.

Description

Technical Field

[0001] The invention belongs to the field of nanotechnology, and in particular relates to a gold nanocluster electrochemiluminescence probe and a preparation method thereof. Background Art

[0002] Electrochemiluminescence refers to the application of a specific potential on the surface of an electrode, causing chemical substances near the electrode to undergo an electrochemical reaction, generating high-energy intermediates or free radicals. Due to its advantages such as no need for exogenous light excitation, low background noise, wide dynamic range and strong controllability, it has demonstrated irreplaceable application value in fields such as biosensing, clinical diagnosis, environmental monitoring and food safety. Electrochemiluminescent materials are the core functional components of electrochemiluminescence systems, and their role runs through the entire process of electron transfer, energy transfer and luminescence. In recent years, electrochemiluminescent materials with excellent biocompatibility and high sensitivity have triggered a research boom in the fields of in vitro diagnosis and biosensing.

[0003] Gold nanoclusters (AuNCs), ultrasmall metallic nanomaterials (<3 nm) with sizes intermediate between atoms and nanoparticles, have become a frontier in electrochemiluminescent (ECL) research due to their discrete electronic energy levels, tunable luminescence properties, excellent biocompatibility, and high surface activity. They exhibit tremendous potential in catalysis, optics, and biomedicine. Despite this, AuNCs as ECL probes are still limited by their high excitation potential, single function, and dependence on co-reactants. Therefore, the research and preparation of co-reactant-free, low-potential AuNC probes could significantly expand the application of ECL sensors in materials science and biomedicine. Summary of the Invention

[0004] The purpose of the present invention is to provide a gold nanocluster electrochemiluminescence probe and a preparation method thereof.

[0005] The technical solution adopted by the present invention is as follows: a gold nanocluster electrochemiluminescent probe, characterized by a multifunctional gold nanocluster obtained by using 2-mercapto-1,3,4-thiadiazole ligand as a reducing agent or protective agent.

[0006] Furthermore, the gold nanocluster electrochemiluminescent probe uses a glassy carbon electrode as a working electrode and adds 2-mercapto-1,3,4-thiadiazole ligand to an electrolyte containing phosphate buffer. Or: The 2-mercapto-1,3,4-thiadiazole ligand was modified on a glassy carbon electrode and used as a working electrode, with phosphate buffer as a co-reactant.

[0007] The present invention also adopts such a technical solution: a method for preparing a gold nanocluster electrochemiluminescent probe, comprising the following steps: 1) The synthesis steps of 2-mercapto-1,3,4-thiadiazole gold nanoclusters are as follows: sodium hydroxide and chloroauric acid solution are added to 2-mercapto-1,3,4-thiadiazole solution, mixed, and then placed in a constant temperature water bath at 25-70°C for constant temperature reaction; after the reaction is completed, the 2-mercapto-1,3,4-thiadiazole-gold nanocluster aqueous solution is purified by dialysis to obtain the 2-mercapto-1,3,4-thiadiazole-gold nanocluster aqueous solution, which is stored in a refrigerator at 4°C in the dark.

[0008] Furthermore, the following steps may be included: 2) Polish the glassy carbon electrode with Al2O3 powder to a smooth mirror surface, then ultrasonically clean it in HNO3 solution (1:1), anhydrous ethanol, and deionized water for 3 minutes, and blow dry it with nitrogen; take the 2-mercapto-1,3,4-thiadiazole gold nanocluster aqueous solution obtained in step 1) and add it dropwise to the treated glassy carbon electrode surface and dry it at room temperature to obtain a gold nanocluster modified glassy carbon electrode.

[0009] Furthermore, in the above step 1), the concentration of sodium hydroxide is 0.1-0.8 mol / L; the concentration of the chloroauric acid solution is 0.005-0.07 mol / L; the concentration of the 2-mercapto-1,3,4-thiadiazole solution is 0.001-0.70 mol / L; and the reaction is carried out in a water bath at a constant temperature for less than 4.0 hours.

[0010] The electrochemiluminescent probe of the present invention actually has two forms: one is 2-mercapto-1,3,4-thiadiazole gold nanoclusters (abbreviated as gold clusters) modified on the electrode, which we call a solid-phase probe; the other is that the gold clusters are independent of the electrode and dissolved in the electrolyte when used, which we call a liquid-phase probe.

[0011] For liquid-phase probes, the generation and detection of electrochemiluminescence signals is as follows: The test was conducted using a three-electrode system, with a glassy carbon electrode as the working electrode, a platinum wire electrode as the counter electrode, and an Ag / AgCl reference electrode. These electrodes were inserted into a phosphate buffer solution containing gold nanoclusters. Cyclic voltammetry was performed with an initial potential of 0 V, a termination potential of 1.4 V, and a scan rate of 0.1 V / s. A photomultiplier tube (PMT) high voltage was set to 700 V to 850 V to detect the electrochemiluminescence signal generated on the working electrode surface.

[0012] For solid-phase probes, the generation and detection of electrochemiluminescence signals is as follows: The test was conducted using a three-electrode system, with a gold nanocluster or gold nanocluster probe-modified glassy carbon electrode as the working electrode, a platinum wire electrode as the counter electrode, and an Ag / AgCl reference electrode. These electrodes were inserted into a phosphate buffer solution, and cyclic voltammetry was performed with an initial potential of 0 V, a termination potential of 1.4 V, and a scan rate of 0.1 V / s. The electrochemiluminescence signal generated on the working electrode surface was detected using a photomultiplier tube (PMT) with a high voltage setting of 700 V to 850 V. The solid-phase ECL signal was significantly enhanced.

[0013] The relative electrochemiluminescence efficiency of the invention is 6.0%; the luminescence potential is 0.60 V, and electrochemiluminescence signals can be generated without adding an external co-reactant.

[0014] The advantages of the present invention are: (1) The present invention adopts a simple direct synthesis method, using 2-mercapto-1,3,4-thiadiazole as a reducing agent and a protective agent to prepare high-performance electrochemiluminescent gold nanocluster probes. The preparation method is simple, easy to operate, and has good reproducibility.

[0015] (2) The electrochemiluminescent gold nanocluster probe obtained in the present invention can generate electrochemiluminescent signals in the absence of a co-reactant, has a low luminescence potential, a high quantum yield and good biocompatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Transmission electron microscopy (TEM) image of 2-mercapto-1,3,4-thiadiazole-gold nanoclusters.

[0017] Figure 2 This is the X-ray photoelectron spectrum of 2-mercapto-1,3,4-thiadiazole-gold nanoclusters.

[0018] Figure 3 This is the electrochemiluminescence-time curve of the glassy carbon electrode in phosphate buffer containing 2-mercapto-1,3,4-thiadiazole-gold nanoclusters.

[0019] Figure 4 This is the electrochemiluminescence-time curve of the 2-mercapto-1,3,4-thiadiazole-gold nanocluster modified glassy carbon electrode.

[0020] Figure 5 This is the electrochemiluminescence-potential curve of the glassy carbon electrode modified with 2-mercapto-1,3,4-thiadiazole-gold nanoclusters. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited thereto. Example 1

[0022] To 2 mL of 0.06 mol / L 2-mercapto-1,3,4-thiadiazole solution, add 0.6 mL of 0.3 mol / L sodium hydroxide and 2 mL of 0.05 mol / L chloroauric acid solution, mix well and place at 30°C for 1 hour. After the reaction, the reaction solution was dialyzed and purified using a dialysis bag with a cutoff molecular weight of 3500 to obtain an aqueous solution of 2-mercapto-1,3,4-thiadiazole gold nanoclusters. Take an appropriate amount of 2-mercapto-1,3,4-thiadiazole protected gold nanocluster solution, treat it with ultrasound and disperse it with ethanol, then drop it on a carbon film copper mesh and dry it at room temperature. The above copper mesh was placed under a field emission transmission electron microscope for morphology observation (see Figure 1 ). Example 2

[0023] To 2 mL of 0.06 mol / L 2-mercapto-1,3,4-thiadiazole solution, add 0.6 mL of 0.3 mol / L sodium hydroxide and 2 mL of 0.05 mol / L chloroauric acid solution, mix well, and place at 30°C with constant temperature stirring for 1.5 hours. After the reaction, the reaction solution was dialyzed and purified using a dialysis bag with a molecular weight cutoff of 3500 to obtain an aqueous solution of 2-mercapto-1,3,4-thiadiazole gold nanoclusters. An appropriate amount of the 2-mercapto-1,3,4-thiadiazole-protected gold nanocluster solution was dropwise cast on a silicon wafer, dried at room temperature, and measured by X-ray photoelectron spectroscopy. Au appeared at 84.8 eV and 88.5 eV. 0 4f 7 / 2 、Au 0 4f 5 / 2 Peak (see Figure 2 ). Example 3

[0024] To 2 mL of a 0.06 mol / L 2-mercapto-1,3,4-thiadiazole solution, 0.6 mL of 0.3 mol / L sodium hydroxide and 2 mL of 0.05 mol / L chloroauric acid were added. The mixture was then stirred at 30°C for 1.5 hours. The reaction mixture was dialyzed through a dialysis bag with a molecular weight cutoff of 3500 to obtain an aqueous solution of 2-mercapto-1,3,4-thiadiazole gold nanoclusters. A 3 mm diameter glassy carbon electrode was polished with 1.0 μm, 0.3 μm, and 0.05 μm Al₂O₃ powders, sequentially polished to a smooth mirror surface. The electrode was then ultrasonically cleaned in HNO₃ solution (concentrated nitric acid:water, volume ratio: 1:1), anhydrous ethanol, and deionized water for 3 minutes and dried under nitrogen. 100 μL of the gold nanocluster solution was added to an electrolyte containing 0.1 mol / L phosphate buffer (pH 11.5). The electrodes were inserted into the electrolyte. Cyclic voltammetry was performed with an initial potential of 0 V, a termination potential of 1.4 V, and a scan rate of 0.1 V / s. The photomultiplier tube high voltage was set to 800 V to detect the electrochemiluminescence signal generated on the working electrode surface. A weak electrochemiluminescence signal was obtained (see Figure 3 ). Example 4

[0025] To 2 mL of a 0.06 mol / L 2-mercapto-1,3,4-thiadiazole solution, 0.6 mL of 0.3 mol / L sodium hydroxide and 2 mL of 0.05 mol / L chloroauric acid were added. The mixture was then stirred at 30°C for 1.5 hours. The reaction mixture was dialyzed through a dialysis bag with a molecular weight cutoff of 3500 to obtain an aqueous solution of 2-mercapto-1,3,4-thiadiazole gold nanoclusters. A 3 mm diameter glassy carbon electrode was polished with 1.0 μm, 0.3 μm, and 0.05 μm Al₂O₃ powders, sequentially to a smooth mirror surface. The electrode was then ultrasonically cleaned for 3 minutes in an HNO₃ solution (concentrated nitric acid:water, volume ratio: 1:1), anhydrous ethanol, and deionized water, followed by drying under nitrogen. 4 μL of 2-mercapto-1,3,4-thiadiazole protected gold nanocluster solution was added dropwise to the treated glassy carbon electrode surface and dried at room temperature to obtain a 2-mercapto-1,3,4-thiadiazole gold nanocluster modified glassy carbon electrode. The gold nanocluster probe modified electrode was inserted into a phosphate buffer solution containing 0.1 mol / L pH 11.5. Cyclic voltammetry was used with an initial potential of 0 V, a termination potential of 1.4 V, and a scan rate of 0.1 V / s. The photomultiplier tube high voltage was set to 800 V to detect the electrochemiluminescence signal generated on the working electrode surface. The electrochemiluminescence signal in the solid phase was significantly enhanced (see Figure 4 ). Example 5

[0026] To 2 mL of a 0.06 mol / L 2-mercapto-1,3,4-thiadiazole solution, 0.6 mL of 0.3 mol / L sodium hydroxide and 2 mL of 0.05 mol / L chloroauric acid were added. The mixture was then stirred at 30°C for 1.5 hours. The reaction mixture was dialyzed through a dialysis bag with a molecular weight cutoff of 3500 to obtain an aqueous solution of 2-mercapto-1,3,4-thiadiazole gold nanoclusters. A 3 mm diameter glassy carbon electrode was polished with 1.0 μm, 0.3 μm, and 0.05 μm Al₂O₃ powders, sequentially to a smooth mirror surface. The electrode was then ultrasonically cleaned for 3 minutes in an HNO₃ solution (concentrated nitric acid:water, volume ratio: 1:1), anhydrous ethanol, and deionized water, followed by drying under nitrogen. 4 μL of 2-mercapto-1,3,4-thiadiazole protected gold nanocluster solution was added dropwise to the treated glassy carbon electrode surface and dried at room temperature to obtain 2-mercapto-1,3,4-thiadiazole gold nanocluster modified glassy carbon electrode. The above gold nanocluster probe modified electrode was inserted into a phosphate buffer solution containing 0.1 mol / L pH 11.5. Cyclic voltammetry was used with an initial potential of 0 V, a termination potential of 1.4 V, and a scan rate of 0.1 V / s. The photomultiplier tube high voltage was set to 800 V to detect the electrochemiluminescence signal generated on the working electrode surface. The electrochemiluminescence signal had a low potential, with a response starting potential of 0.40 V and reached the maximum ECL intensity at 0.60 V (see Figure 5 ). Example 6

[0027] A glassy carbon electrode was modified with 2-mercapto-1,3,4-thiadiazole gold nanoclusters. The prepared gold nanocluster probe-modified glassy carbon electrode was inserted into a 0.1 mol / L pH 11.5 phosphate buffer solution. Cyclic voltammetry was performed using a linear sweep voltage from 0 V to 1.4 V at a scan rate of 0.2 V / s. The photomultiplier tube high voltage was set to 550 V. The electrochemiluminescence signal (I) generated on the working electrode surface was detected. The corresponding charge generated was Q. f In addition, a glassy carbon electrode with a diameter of 3 mm was polished and ground with 1.0 μm, 0.3 μm, and 0.05 μm Al2O3 powders in sequence to a smooth mirror surface. It was then ultrasonically cleaned in HNO3 solution (1:1), anhydrous ethanol, and deionized water for 3 minutes and dried with N2. A three-electrode system was used, with a bare glassy carbon electrode as the working electrode, a platinum wire electrode as the counter electrode, and Ag / AgCl as the reference electrode. The bare glassy carbon electrode was inserted into a solution containing 1.0 mmol / L [Ru(bpy)3] 2+and 0.1 mol / L tetrabutylammonium perchlorate in acetonitrile solution, applying a scanning voltage of -1.0 to -1.8 V at a scanning speed of 0.2 V / s and a photomultiplier tube high voltage setting of 550 V to detect the electrochemiluminescence signal generated on the working electrode surface ( I °) The corresponding amount of electricity generated is Q ° f By the formula Φ ECL = Φ ° ECL ( IQ ° f / I ° Q f ) Calculate the electrochemiluminescence efficiency of the gold nanocluster probe Φ ECL It is 6.0%.

[0028] The above description is only a typical embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A gold nanocluster electrochemiluminescent probe, characterized by Multifunctional gold nanoclusters obtained using 2-mercapto-1,3,4-thiadiazole ligand as reducing agent or protecting agent.

2. The gold nanocluster electrochemiluminescence probe according to claim 1, wherein: A glassy carbon electrode was used as the working electrode, and 2-mercapto-1,3,4-thiadiazole ligand was added to an electrolyte containing phosphate buffer.

3. The gold nanocluster electrochemiluminescence probe according to claim 1, wherein: The 2-mercapto-1,3,4-thiadiazole ligand was modified on a glassy carbon electrode and used as a working electrode, with phosphate buffer as a co-reactant.

4. A method for preparing a gold nanocluster electrochemiluminescent probe, comprising the following steps: 1) The synthesis steps of 2-mercapto-1,3,4-thiadiazole gold nanoclusters are as follows: sodium hydroxide and chloroauric acid solution are added to 2-mercapto-1,3,4-thiadiazole solution, mixed, and then placed in a constant temperature water bath at 25-70°C for constant temperature reaction; after the reaction is completed, the 2-mercapto-1,3,4-thiadiazole-gold nanocluster aqueous solution is purified by dialysis to obtain the 2-mercapto-1,3,4-thiadiazole-gold nanocluster aqueous solution, which is stored in a refrigerator at 4°C in the dark.

5. The method for preparing a gold nanocluster electrochemiluminescent probe according to claim 4, wherein: The following steps are also included: 2) Polish the glassy carbon electrode with Al2O3 powder to a smooth mirror surface, then ultrasonically clean it in HNO3 solution (1:1), anhydrous ethanol, and deionized water for 3 minutes, and blow dry it with nitrogen; take the 2-mercapto-1,3,4-thiadiazole gold nanocluster aqueous solution obtained in step 1) and add it dropwise to the treated glassy carbon electrode surface and dry it at room temperature to obtain a gold nanocluster modified glassy carbon electrode.

6. The method for preparing a gold nanocluster electrochemiluminescent probe according to claim 4 or 5, characterized in that: In the above step 1), the concentration of sodium hydroxide is 0.1-0.8 mol / L; the concentration of the chloroauric acid solution is 0.005-0.07 mol / L; the concentration of the 2-mercapto-1,3,4-thiadiazole solution is 0.001-0.70 mol / L; and the reaction is carried out in a water bath at a constant temperature for less than 4.0 hours.

Images