A rapid detection method for sulfur-containing gases based on an efficient fluorescence-SERS sensing platform

Abstract

The present invention specifically relates to a rapid detection method for sulfur-containing gases based on an efficient fluorescence-SERS sensing platform, belonging to the technical field of food safety detection. The present invention proposes a seed growth strategy for preparing core-shell MOF-5-NH2 functionalized gold-silver core-shell nanoparticles (Au@Ag NPs). This strategy is to first prepare the Au@Ag NPs core, and then modify it with polyvinylpyrrolidone so that the MOF-5-NH2 shell can grow stably. Through the high specific surface area and porosity of the MOF material, H2S gas can be enriched onto the Au@Ag NPs core, and the reaction of H2S with the Au@Ag NPs core can be monitored by SERS. At the same time, the MOF-5-NH2 shell can also enrich SO2 gas onto the surface and bind with amino groups, and can be visually detected by fluorescence spectroscopy or ultraviolet light.

Description

Technical Field

[0001] The present invention specifically relates to a method for rapid detection of sulfur-containing gas based on a high-efficiency fluorescence-SERS sensing platform, and belongs to the technical field of food safety detection. Background Art

[0002] H2S and SO2 are common air pollutants, which are widely distributed in the environment through the chemical industry, petroleum industry, natural gas and other fields. H2S has a strong pungent odor, which can damage the human nervous system and has a strong irritating effect on human mucous membranes. 2- and HSO 3- Two forms are dissolved in water. Its derivatives are easily oxidized to form sulfates, which are the main components of acid rain. In addition, excessive inhalation of SO2 is associated with some respiratory, nervous and cardiovascular diseases and lung cancer. Therefore, monitoring the concentrations of H2S and SO2 and protecting them are essential for maintaining human health. Traditional detection methods include titration, physicochemical adsorption, electrochemical methods and chromatography, etc. These instruments and equipment are expensive, the detection cost is high, and the steps are cumbersome, and they cannot meet the requirements for rapid detection of sulfur-containing gases. The present invention proposes a method for rapid detection of sulfur-containing gases based on a high-efficiency fluorescence-SERS sensing platform, which overcomes the shortcomings of traditional methods and improves the speed and sensitivity of H2S and SO2 detection in food. Summary of the invention

[0003] The purpose of the present invention is to overcome the technical defects existing in the existing detection technology, such as: high detection cost, long detection time, cumbersome detection steps, etc. The present invention provides a method for rapid detection of sulfur-containing gas based on an efficient fluorescence-SERS sensing platform, and proposes a seed growth strategy for preparing gold and silver core-shell nanoparticles (Au@Ag NPs) functionalized with core-shell MOF-5-NH2. The strategy is to first prepare the Au@Ag NPs core, and then modify it with polyvinyl pyrrolidone so that the MOF-5-NH2 shell can grow stably. Through the high specific surface area and porosity of the MOF material, H2S gas can be enriched in the Au@Ag NPs core, and the reaction of H2S with the Au@Ag NPs core can be monitored by SERS. At the same time, the MOF-5-NH2 shell can also enrich SO2 gas to the surface and combine with amino groups, which can be detected by naked eyes through fluorescence spectroscopy or ultraviolet light.

[0004] Specifically, the technical solution adopted by the present invention is: a method for rapid detection of sulfur-containing gas based on a high-efficiency fluorescence-SERS sensing platform, comprising the following steps:

[0005] Step 1, preparation of gold-silver core-shell nanoparticles (Au@Ag NPs): Au@Ag NPs were prepared by a seed-mediated two-step growth method, wherein a tetrachloroauric acid (HAuCl4·4H2O) solution was heated to boiling, and then a sodium citrate (C6H5Na3O7) solution was quickly added to continue the reaction, followed by a silver nitrate (AgNO3) solution being added dropwise until the reaction solution turned orange-yellow, and then naturally cooled to room temperature to obtain Au@Ag NPs;

[0006] Step 2, Au@Ag NPs surface modification: adding polyvinyl pyrrolidone (PVP) solution into Au@Ag NPs solution, and performing PVP modification under magnetic stirring;

[0007] Step 3, functional modification of Au@Ag NPs: Disperse zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in N,N-dimethylformamide (DMF) solution, add PVP-modified Au@Ag NPs, mix well, and then add 2-amino-terephthalic acid to the DMF solution. Then slowly add triethylamine solution to the above solution, and continue stirring after a white precipitate is formed. Wash with dichloromethane (DCM), filter and dry the sample in a vacuum drying oven, and finally collect the light yellow powder sample for use to obtain MOF-5-NH2 functionalized Au@Ag NPs;

[0008] Step 4, construction of the detection system: dissolve the Au@Ag NPs functionalized with MOF-5-NH2 in ethanol, and prepare three sample solutions at the same time. Add 4-mercaptophenylboronic acid (4-MPBA) to the first solution, mix thoroughly, and collect the SERS spectrum under the Raman instrument. Then, add sodium sulfide (Na2S) solution, mix thoroughly, and collect the SERS spectrum again. Irradiate the second solution with ultraviolet light first, and collect the fluorescence spectrum. Then, add sodium sulfite (Na2SO3) solution, irradiate with ultraviolet light again, and collect the fluorescence spectrum. Add Na2S and Na2SO3 solutions to the third solution at the same time, collect the SERS spectrum first, and then collect the fluorescence spectrum.

[0009] Furthermore, the Au@Ag NPs can change the SERS signal through redox reaction and the action of H2S gas.

[0010] Furthermore, the MOF-5-NH2 can form a stable 1:1 complex with SO2 gas, resulting in charge transfer, thereby producing a fluorescence on or off effect.

[0011] Furthermore, the MOF-5-NH2 has a porous structure and strong adsorption capacity, and H2S and SO2 gases can be adsorbed by MOF-5-NH2 functionalized Au@Ag NPs, thereby enhancing the interaction between the composite material and the analytes.

[0012] Furthermore, in the step 1, the concentration range of the HAuCl4·4H2O solution is 0.1-2 mM, the concentration range of the C6H5Na3O7 solution is 0.1-10 wt%, the reaction time is 10-60 min, and the concentration range of the added AgNO3 solution is 1-3 mM.

[0013] Furthermore, in step 2, the volume of PVP is in the range of 1-5 mL, the concentration of Au@Ag NPs is in the range of 0.1-1 nM, and the stirring time is in the range of 1-12 h.

[0014] Further, in step three, the concentration range of Zn(NO3)2·6H2O is 0.001-0.005 mol, the volume range of DMF is 10-50 mL, the concentration range of added 2-amino-terephthalic acid is 0.001-0.005 mol, the concentration range of triethylamine is 0.005-0.01 mol, the stirring time range is 0.5-3 h, and the drying time range is 1-3 h.

[0015] Further, in step 4, the volume range of the MOF-5-NH2 functionalized Au@Ag NPs is 5-20 μL, and the concentration of the 4-MPBA solution is 0.01M.

[0016] Compared with the existing detection technology, the beneficial effects of the present invention are as follows:

[0017] 1. The present invention discloses a method for rapid detection of sulfur-containing gases based on an efficient fluorescence-SERS sensing platform, and proposes a seed growth strategy for preparing gold-silver core-shell nanoparticles (Au@AgNPs) functionalized with core-shell MOF-5-NH2. The strategy is to first prepare the Au@Ag NPs core, and then modify it with polyvinyl pyrrolidone so that the MOF-5-NH2 shell can grow stably. The high specific surface area and porosity of the MOF material can enrich H2S gas to the Au@Ag NPs core, and the reaction of H2S with the Au@Ag NPs core can be monitored by SERS. At the same time, the MOF-5-NH2 shell can also enrich SO2 gas to the surface and combine with amino groups, which can be detected by naked eyes through fluorescence spectroscopy or ultraviolet light.

[0018] 2. The fluorescence-SERS sensing detection system constructed by the present invention, the specifically designed Au@Ag NPs can change the SERS signal through redox reaction and the action of H2S gas.

[0019] 3. The fluorescence-SERS sensing detection system constructed by the present invention is specifically designed that MOF-5-NH2 can form a stable 1:1 complex with SO2 gas, resulting in charge transfer, thereby producing a fluorescence on or off effect.

[0020] 4. The fluorescence-SERS sensing detection system constructed by the present invention specifically designs MOF-5-NH2 with a porous structure and strong adsorption capacity, and H2S and SO2 gases can be adsorbed by Au@Ag NPs functionalized with MOF-5-NH2, thereby enhancing the interaction between the composite material and the analyte.

[0021] The sulfur-containing gas rapid detection method based on the efficient fluorescence-SERS sensing platform established in the present invention can detect H2S and SO2 in the range of 5-60nM and 0-100nM respectively, does not require expensive instruments, is faster than traditional colorimetry, and has the potential for online application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Detection Schematic Diagram

[0023] Figure 2 Scanning electron microscopy images of MOF-5-NH2 prepared by the present invention at different scales;

[0024] Figure 3 Transmission electron microscopy image of Au@Ag NPs prepared by the present invention;

[0025] Figure 4 The present invention provides a standard curve for H2S detection based on SERS probe;

[0026] Figure 5 The present invention is based on the standard curve of SO2 detection of fluorescent probe. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0029] Embodiment 1:

[0030] The present invention discloses a method for rapid detection of sulfur-containing gas based on a high-efficiency fluorescence-SERS sensing platform, and the specific steps are as follows:

[0031] Step 1, preparation of gold-silver core-shell nanoparticles (Au@Ag NPs): Au@Ag NPs were prepared by a seed-mediated two-step growth method, 0.25 mM HAuCl4·4H2O solution was heated to boiling, and then C6H5Na3O7 (1%) solution was quickly added to continue the reaction, followed by dropwise addition of 1 mM AgNO3 solution until the reaction solution turned orange-yellow, and then naturally cooled to room temperature to obtain Au@AgNPs;

[0032] Step 2, Au@Ag NPs surface modification: 3 mL of PVP solution was added to 0.5 nM Au@Ag NPs solution and magnetically stirred for 12 h for PVP modification;

[0033] Step 3, functional modification of Au@Ag NPs: Disperse 0.004 mol Zn(NO3)2·6H2O in DMF solution, add PVP-modified Au@Ag NPs, mix well, and then add 0.002 mol of 2-amino-terephthalic acid to the DMF solution. Then slowly add 0.006 mol triethylamine solution to the above solution, and continue stirring for 2 hours after a white precipitate is formed. Wash with dichloromethane (DCM) three times, filter and place the sample in a vacuum drying oven, dry at 120°C for 2 hours, and finally collect the light yellow powder sample for use to obtain MOF-5-NH2 functionalized Au@Ag NPs;

[0034] Step 4, construction of the detection system: dissolve the Au@Ag NPs functionalized with MOF-5-NH2 in ethanol, and prepare 3 sample solutions (10 μL) at the same time. Add 4-MPBA (0.01M) to the first solution, mix thoroughly, and collect the SERS spectrum under the Raman instrument. Then, add sodium sulfide (Na2S) solution, mix thoroughly, and collect the SERS spectrum again. The second solution is first irradiated with ultraviolet light, and the fluorescence spectrum is collected. Then, sodium sulfite (Na2SO3) solution is added, and it is irradiated with ultraviolet light again and the fluorescence spectrum is collected. The third solution is added with Na2S and Na2SO3 solutions at the same time, and the SERS spectrum is collected first, and then the fluorescence spectrum is collected. The relationship curves between the concentrations of Na2S and Na2SO3 and the SERS signal and fluorescence spectrum intensity are established respectively. The results show that the linear relationship between the Na2S concentration and the SERS signal intensity is y=-353.82x+27895.41, R 2 =0.9868, the linear relationship between Na2SO3 concentration and fluorescence spectrum intensity is F / F0=0.0207c+0.8567, R 2 =0.9938.

[0035] Figure 1 This is the detection principle diagram; Figure 2 Scanning electron microscope images of MOF-5-NH2 prepared in the present invention at different scales; Figure 3 Transmission electron microscopy image of Au@Ag NPs prepared in the present invention; Figure 4 This is the standard curve for H2S detection based on the SERS probe of the present invention; Figure 5 This is the standard curve for SO2 detection based on the fluorescent probe of the present invention.

[0036] In summary, the present invention has developed a seed growth method to prepare MOF-5-NH2 functionalized Au@Ag NPs, which can detect H2S and SO2 by SERS and fluorescence spectroscopy, respectively. The method enables MOF-5-NH2 material to grow around Au@Ag NPs by modifying Au@Ag NPs. Due to the high specific surface area and high porosity of MOF-5-NH2, it can enrich the analyte. The uniqueness of the prepared composite material is that: (1) the core-shell MOF-5-NH2 functionalized Au@Ag NPs has excellent adsorption properties, making it an excellent SERS substrate for highly selective and sensitive detection of analytes; (2) since Au@Ag NPs can detect hydrogen sulfide by SERS, MOF-5-NH2 can detect sulfur dioxide by fluorescence spectroscopy, and they do not interfere with each other, MOF-5-NH2 functionalized Au@Ag NPs can detect these two substances at the same time, greatly improving the detection efficiency, making it more convenient, fast and environmentally friendly.

[0037] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for rapid detection of sulfur-containing gas based on an efficient fluorescence-SERS sensing platform, characterized in that: The sulfur-containing gas is SO2 and H2S, comprising the following steps: Step 1, preparation of gold-silver core-shell nanoparticles (Au@Ag NPs): Au@Ag NPs were prepared by a seed-mediated two-step growth method, wherein a tetrachloroauric acid (HAuCl4·4H2O) solution was heated to boiling, and then a sodium citrate (C6H5Na3O7) solution was quickly added to continue the reaction, followed by a silver nitrate (AgNO3) solution added dropwise until the reaction solution turned orange-yellow, and then naturally cooled to room temperature to obtain Au@Ag NPs; Step 2, Au@Ag NPs surface modification: polyvinyl pyrrolidone (PVP) solution was added to the Au@Ag NPs solution, and PVP modification was performed under magnetic stirring; Step 3, functionalization modification of Au@Ag NPs: Disperse zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in N,N-dimethylformamide (DMF) solution, add PVP-modified Au@Ag NPs, mix well, add 2-amino-terephthalic acid to DMF solution, and then slowly add triethylamine solution to the above solution. Continue stirring after forming a white precipitate, then wash with dichloromethane (DCM), filter and dry the sample in a vacuum drying oven, finally collect the light yellow powder sample for use, and obtain MOF-5-NH2 functionalized Au@Ag NPs; Step 4, construction of the detection system: dissolve the MOF-5-NH2 functionalized Au@Ag NPs in ethanol, and prepare 3 sample solutions at the same time. Add 4-mercaptophenylboric acid (4-MPBA) to the first solution, mix thoroughly and collect the SERS spectrum under the Raman instrument. Then add sodium sulfide (Na2S) solution and mix thoroughly and collect the SERS spectrum again. The second solution is first irradiated with ultraviolet light and the fluorescence spectrum is collected. Then add sodium sulfite (Na2SO3) solution, irradiate with ultraviolet light again and collect the fluorescence spectrum. The third solution is added with Na2S and Na2SO3 solutions at the same time, first collect the SERS spectrum and then collect the fluorescence spectrum.

2. The method for rapid detection of sulfur-containing gas based on a high-efficiency fluorescence-SERS sensing platform according to claim 1, characterized in that: Au@Ag NPs change the SERS signal through redox reaction and H2S gas action.

3. The method for rapid detection of sulfur-containing gas based on a high-efficiency fluorescence-SERS sensing platform according to claim 1, characterized in that: MOF-5-NH2 can form a stable 1:1 complex with SO2 gas, resulting in charge transfer, thus producing a fluorescence on or off effect.

4. The method for rapid detection of sulfur-containing gas based on a high-efficiency fluorescence-SERS sensing platform according to claim 1, characterized in that: The MOF-5-NH2 has a porous structure and adsorption capacity, and H2S and SO2 gases can be adsorbed by Au@Ag NPs functionalized with MOF-5-NH2, thereby enhancing the interaction between the composite material and the analyte.

5. The method for rapid detection of sulfur-containing gas based on a high-efficiency fluorescence-SERS sensing platform according to claim 1, characterized in that: In step 1, the concentration range of the HAuCl4·4H2O solution is 0.1-2 mM, the concentration range of the C6H5Na3O7 solution is 0.1-10 wt %, the reaction time is 10-60 min, and the concentration range of the added AgNO3 solution is 1-3 mM.

6. The method for rapid detection of sulfur-containing gas based on a high-efficiency fluorescence-SERS sensing platform according to claim 1, characterized in that: In step 2, the PVP volume range is 1-5 mL, the Au@Ag NPs concentration range is 0.1-1 nM, and the stirring time range is 1-12 h.

7. The method for rapid detection of sulfur-containing gas based on a high-efficiency fluorescence-SERS sensing platform according to claim 1, characterized in that: In step three, the concentration range of Zn(NO3)2·6H2O is 0.001-0.005 mol, the volume range of DMF is 10-50 mL, the concentration range of added 2-amino-terephthalic acid is 0.001-0.005 mol, the concentration range of triethylamine is 0.005-0.01 mol, the stirring time range is 0.5-3 h, and the drying time range is 1-3 h.

8. The method for rapid detection of sulfur-containing gas based on a high-efficiency fluorescence-SERS sensing platform according to claim 1, characterized in that: In step 4, the volume range of the MOF-5-NH2 functionalized Au@Ag NPs sample was 5-20 μL, and the concentration of the 4-MPBA solution was 0.01 M.

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