Fluorescent-Raman bimodal probe for hydrogen sulfide detection and preparation method and application thereof

Abstract

The invention belongs to the technical field of analysis and detection, and particularly relates to a fluorescent-Raman bimodal probe for hydrogen sulfide detection and a preparation method and application of the fluorescent-Raman bimodal probe for hydrogen sulfide detection. Specifically, 4-nitrobenzenethiol (4-NTP) modified silver nanocluster-gold nanoparticles are encapsulated in ZIF-8 to form the silver nanocluster / gold nanoparticle composite material. Compared with the prior art, the SERS probe material for hydrogen sulfide detection overcomes the defects that in the prior art, an SERS probe material for hydrogen sulfide detection is prone to interference and insufficient in reliability and sensitivity. According to the scheme, hydrogen sulfide is effectively enriched through introduction of the ZIF-8 metal organic framework, a detection signal is remarkably enhanced, the material can specifically recognize hydrogen sulfide, the response speed is high, the detection sensitivity is high, and the detection range is 10 <-13 >-10 <-3 > M.

Description

Technical Field

[0001] The present invention belongs to the technical field of analytical detection, and particularly relates to a fluorescence-Raman dual-mode probe for hydrogen sulfide detection, a preparation method thereof, and an application thereof. Background Art

[0002] As is well known, hydrogen sulfide (H2S) is a highly toxic gas, and its potential to block cell respiration by binding to iron present in the cytochrome enzyme of mitochondria. It is a volatile sulfur-containing compound that is widely present in sulfur-rich foods and is mainly produced during the decomposition of protein substances such as meat, eggs, fruits, and vegetables. In the field of biomedical research, due to the effective role of hydrogen sulfide as a signaling molecule (gasotransmitter) in biological systems, the utilization of hydrogen sulfide has been actively explored, similar to the cases of carbon monoxide (CO) and nitric oxide (NO). In addition, it has been observed that endogenous hydrogen sulfide molecules are involved in various physiological functions, such as the hyperpolarization of vascular smooth muscle and cardioprotection through anti-apoptotic and antioxidant signaling effects. Hydrogen sulfide is involved in regulating blood pressure, promoting angiogenesis, inhibiting inflammatory responses, and regulating neurotransmitter release. Given the importance of hydrogen sulfide in food safety and biomedical research, the development of highly sensitive and user-friendly hydrogen sulfide detection methods has become an urgent task. These technologies can not only monitor food spoilage in real time, thereby improving food safety, but also improve health monitoring and disease diagnosis. Therefore, the progress of rapid and efficient hydrogen sulfide detection strategies is crucial for improving food industry standards and ensuring public health. Traditional hydrogen sulfide detection methods such as methylene blue spectrophotometry, high-performance liquid chromatography, gas chromatography, and electrochemical analysis are effective, but generally rely on complex instruments, professional operations, and high-cost pretreatment, making it difficult to achieve rapid in-situ detection. Single-mode detection systems are vulnerable to environmental fluctuations or probe inactivation due to the single signal source, and it is difficult to balance stability and accuracy.

[0003] Surface-enhanced Raman spectroscopy (SERS) significantly amplifies the Raman scattering signal of molecules based on a specific nanostructured substrate, and its core mechanism includes local surface plasmon resonance and chemical enhancement effects. Through the synergistic effect of electromagnetic field enhancement and charge transfer, this technology can obtain molecular fingerprint information of analytes at trace levels, with the advantages of ultra-high sensitivity and specificity. By constructing metal / metal-organic framework composite nanomaterials (NPs / MOFs), the affinity between the substrate and the target molecule hydrogen sulfide can be significantly enhanced, promoting the efficient contact of hydrogen sulfide with the hot spot regions on the surface of the SERS substrate and improving the sensitivity and selectivity of detection. Due to the interaction between the building units, this nanoparticle assembly exhibits unique performance advantages compared to a single entity.

[0004] As disclosed in CN110514640A, a surface-enhanced Raman spectroscopy detection technique based on an inorganic sensitive layer and its material preparation are provided. In this detection technique, a surface-enhanced Raman spectroscopy material based on an inorganic sensitive layer is used as an active substrate for surface-enhanced Raman scattering and exposed to a small molecule atmosphere. A Raman spectrometer is used to detect a new solid substance formed by the specific reaction between the inorganic sensitive layer and the small molecule to be detected. The type of small molecule is obtained from the Raman spectrum of the new solid substance, where the small molecule includes hydrogen sulfide molecules. However, the SERS enhancement effect of the single metal nanoparticle in this invention is limited, and the inorganic sensitive layer of this invention is a single inorganic material, lacking the molecular specific recognition function, which may lead to cross-interference.

[0005] In addition, as disclosed in CN119269472A, a SERS nanoprobe for hydrogen sulfide detection and its preparation method are provided. The SERS nanoprobe for hydrogen sulfide detection is a core-shell-satellite structure composed of gold nanoparticles and a metal-organic framework structure (MOF), simply referred to as Au@ZIF-8@Au. However, the SERS nanoprobe of this invention is a SERS unimodal probe. Furthermore, other sulfur-containing small molecules (such as thiol, thioether, sulfur dioxide) may undergo non-specific adsorption or chemical reaction with the surface of DTPA or gold nanoparticles, resulting in the risk of false positives in its detection results.

[0006] Therefore, it is necessary to design a new type of probe for hydrogen sulfide detection to reduce the probability of misjudgment and improve the anti-interference ability, thereby providing a new strategy with high selectivity, sensitivity and convenience for hydrogen sulfide detection. Summary of the Invention

[0007] The purpose of the present invention is to provide a fluorescence-Raman bimodal probe for hydrogen sulfide detection, its preparation method and application to solve at least one of the above problems, so as to solve the defects of the SERS probe material for hydrogen sulfide detection in the prior art, such as being easily interfered, insufficient reliability and sensitivity. The introduction of the ZIF-8 metal-organic framework in this solution effectively enriches hydrogen sulfide, significantly enhances the detection signal, and this material can specifically recognize hydrogen sulfide, with a fast response speed and high detection sensitivity, and its detection range is between 10 -13 -10 -3 M.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] The first aspect of the present invention discloses a fluorescence-Raman bimodal probe for hydrogen sulfide detection. The fluorescence-Raman bimodal probe is composed of modified silver nanoclusters-gold nanoparticles encapsulated in ZIF-8 (AgAuNPs@ZIF-8 / 4-NTP), and this fluorescence-Raman bimodal probe is a composite structure based on noble metal-MOFs;

[0010] Among them,

[0011] The modified silver nanocluster-gold nanoparticles are silver nanocluster-gold nanoparticles modified with 4-nitrobenzenethiol (AgAuNPs / 4-NTP);

[0012] The silver nanocluster-gold nanoparticles are gold nanoparticles coated with a silver nanocluster coating on the surface (AgAuNPs).

[0013] The second aspect of the present invention discloses a preparation method of the fluorescence-Raman dual-modal probe for hydrogen sulfide detection as described above, including the following steps:

[0014] (1) Synthesize gold nanoparticles by the sodium citrate reduction method:

[0015] Use an aqueous sodium citrate solution as a reducing agent to react with a chloroauric acid solution to synthesize gold nanoparticles;

[0016] (2) Synthesize silver nanocluster-gold nanoparticles by the in-situ growth method:

[0017] Use a bovine serum albumin solution as a linker and a stabilizer to uniformly coat the gold nanoparticles, then add a silver nitrate solution, adjust the pH to alkaline and then add sodium borohydride for reduction to form gold nanoparticles coated with a silver nanocluster coating on the surface;

[0018] (3) Obtain the fluorescence-Raman dual-modal probe by the self-assembly method:

[0019] Modify 4-nitrobenzenethiol on the surface of the silver nanocluster-gold nanoparticles by the self-assembly method, and wrap it in ZIF-8 by the solvent method.

[0020] Preferably, in step (1), add the aqueous sodium citrate solution after heating the chloroauric acid solution to boiling, and stop heating after the color changes to obtain a gold nanoparticle colloid;

[0021] The concentration of the aqueous sodium citrate solution is 1 wt%, the concentration of the chloroauric acid solution is 0.01 wt%, and the volume ratio of the aqueous sodium citrate solution to the chloroauric acid solution is 1.5:130.

[0022] Preferably, in step (2),

[0023] The concentration of the bovine serum albumin solution is 0.38 mM, the concentration of the gold nanoparticles is 0.45 nM, and the volume ratio of the bovine serum albumin solution to the gold nanoparticles is 20 mL:500 μL;

[0024] The concentration of the silver nitrate solution is 0.5 M, and the volume ratio of the silver nitrate solution to the gold nanoparticles is 1 mL:500 μL.

[0025] Preferably, in step (3), the self-assembly method includes the following steps:

[0026] Add a 4-nitrobenzenethiol solution to the silver nanocluster-gold nanoparticle solution, incubate and then centrifuge; collect the precipitate and redisperse it to obtain 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticles.

[0027] Preferably, the concentration of the silver nanocluster-gold nanoparticle solution is 0.45 nM, the concentration of the 4-nitrobenzenethiol solution is 0.1 mM, and the volume ratio of the silver nanocluster-gold nanoparticle solution to the 4-nitrobenzenethiol solution is 10 mL:0.1 mL;

[0028] The incubation is carried out at room temperature for 2 hours.

[0029] Preferably, in step (3), the solvent method includes the following steps:

[0030] Add an aqueous solution of cetyltrimethylammonium bromide (CTAB) to a 2-methylimidazole solution, sequentially add a zinc nitrate hexahydrate (Zn(NO3)2·6H2O) solution and a 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticle solution, stir and then let stand, incubate and then centrifuge to obtain a fluorescence-Raman dual-mode probe.

[0031] Preferably, the concentration of the cetyltrimethylammonium bromide aqueous solution is 1×10 -3 M, the concentration of the 2-methylimidazole solution is 1.32 M, the concentration of the zinc nitrate hexahydrate solution is 2.4×10 -2 M, the concentration of the 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticle solution is 0.4 nM, and the volume ratio of the cetyltrimethylammonium bromide aqueous solution, the 2-methylimidazole solution, the zinc nitrate hexahydrate solution to the 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticle solution is 0.144 mL:1 mL:1 mL:1 mL;

[0032] The standing is carried out at room temperature for 3 h;

[0033] The incubation is carried out at 30 °C for 30 s.

[0034] The third aspect of the present invention discloses an application of the fluorescence-Raman dual-mode probe for hydrogen sulfide detection as described above in the technical field of hydrogen sulfide detection.

[0035] Preferably, mix an aqueous solution containing the fluorescence-Raman dual-mode probe with a sodium hydrosulfide (NaHS) solution for reaction, and perform dual-mode detection after the reaction;

[0036] The dual-mode detection includes fluorescence analysis and SERS detection;

[0037] The fluorescence analysis uses a 465 nm excitation light source;

[0038] The SERS detection uses a 785 nm laser to excite for 20 s.

[0039] The working principle of the present invention is as follows:

[0040] Based on the precipitation reaction of hydrogen sulfide with silver (Ag + ) nanoclusters, the fluorescence intensity is weakened. At the same time, hydrogen sulfide undergoes a reduction reaction with the nitro group on the benzene ring of 4-nitrobenzenethiol, generating a new characteristic peak at 1591 cm -1 in the Raman spectrum. In addition, the introduction of the ZIF-8 metal-organic framework effectively enriches hydrogen sulfide and significantly enhances the detection signal.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The preparation method of the present invention is simple and easy to implement. Compared with the prior art, the introduction of the ZIF-8 metal-organic framework effectively enriches hydrogen sulfide, and the encapsulation of the MOFs material in this scheme can provide selective adsorption and chemical protection, with good stability. At the same time, the dual-metal nanoparticles (silver-gold synergistically enhance the SERS signal) in this scheme can significantly improve the sensitivity through the surface plasmon coupling effect, significantly enhancing the detection signal. The obtained fluorescence-Raman dual-modal probe material can specifically recognize hydrogen sulfide, with high sensitivity and fast response speed.

[0043] The fluorescence-Raman dual-modal probe in this scheme integrates the advantages of fluorescence and SERS technologies, realizes double-signal verification in the detection of hydrogen sulfide, and improves the sensitivity; moreover, the dual-signal mechanism reduces the risk of false positives / negatives. When the two signals respond simultaneously, the detection result is more reliable, and it has potential application prospects in the fields of biological imaging, environment, etc.

[0044] (1) The present invention uses bovine serum albumin as a stabilizer and linker, in-situ reduces silver nanoclusters on the surface of gold nanoparticles to synthesize a composite gold-silver nanomaterial with fluorescence effect, and further prepares a composite material through self-assembly and solvent methods. The process is simple and convenient for popularization and use.

[0045] (2) The present invention uses a fluorescence and Raman dual-modal probe mode to detect hydrogen sulfide, with a fast response speed and high detection sensitivity. The detection range is between 10 -13 -10 -3 M. The lowest concentration that can be detected by the fluorescence-Raman spectrum dual-modal probe can reach 10 -13 M, and the detection limit is low.

[0046] (3) The fluorescence-Raman dual-mode probe of the present invention can rapidly respond to hydrogen sulfide, inducing a reduction reaction between nitro and hydrogen sulfide to generate amino group. By analyzing the Raman characteristic peaks of different functional groups, the Raman shift of nitro is 1565±2 cm -1 , and that of amino group is 1591±2 cm -1 . Therefore, it can effectively detect low-concentration hydrogen sulfide.

[0047] (4) The present invention selects CTAB as a stabilizer to promote the effective encapsulation of core-shell structured AgAuNPs / 4-NTP in ZIF-8 crystals. Its functions are mainly reflected in two aspects: 1) As a cationic surfactant, it effectively regulates the nucleation and growth processes of ZIF-8 crystals; 2) By forming an ordered molecular layer on the surface of metal nanoparticles, it significantly enhances the interfacial interaction between nanoparticles and the ZIF-8 matrix, thereby optimizing the structural stability of the composite material.

[0048] (5) The introduction of metal-organic framework material (ZIF-8) effectively enriches hydrogen sulfide and significantly enhances the detection signal. Therefore, the fluorescence-Raman dual-mode probe of the present invention exhibits high selectivity and quantitative detection ability for hydrogen sulfide in biological samples, verifying the practicality and biological significance of the dual-mode probe material.

[0049] (6) In the present invention, the fluorescence detector selects an excitation wavelength of 465 nm, and the Raman spectrometer selects an excitation wavelength of 785 nm. At 675±2 nm, the fluorescence intensity decreases with the increase of hydrogen sulfide concentration, and a new Raman characteristic peak appears at a Raman shift of 1591±2 cm -1 . Therefore, the present invention can quantitatively detect molecular hydrogen sulfide.

[0050] (7) Using the dual-mode probe material of the present invention for fluorescence detection, hydrogen sulfide can be distinguished from Na + , K + , Zn 2+ , Cl - , Cys; for Raman detection, hydrogen sulfide can be distinguished from F - , Br - , CH3COO - , . It has strong specificity. Thus, through the characteristics of dual-mode response, it can achieve specific detection of hydrogen sulfide in a complex environment and avoid the risk of potential false positives.

[0051] The present invention uses a fluorescence-Raman dual-mode probe to detect hydrogen sulfide, with a fast response speed and high detection sensitivity. Its detection range is from 10 -13 to 10 -3Between 10 -13 M, with a low detection limit.

[0052] In summary, the fluorescence-Raman dual-modal probe material and its preparation method for rapid and accurate on-site detection of hydrogen sulfide provided by the present invention provide a simple and general dual-modal sensing strategy, thus enabling highly sensitive, highly selective, and recyclable detection of hydrogen sulfide, and laying a foundation for rapid, real-time, and accurate on-line detection of hydrogen sulfide. Description of the Drawings

[0053] Figure 1 TEM image of AuNPs synthesized in Example 1;

[0054] Figure 2 TEM image of AgAuNPs@ZIF-8 / 4-NTP synthesized in Example 2;

[0055] Figure 3 Fluorescence spectra of the fluorescence-Raman dual-modal probe for different ions in Example 3;

[0056] Figure 4 Raman spectra of the fluorescence-Raman dual-modal probe for different ions in Example 3;

[0057] Figure 5 Fluorescence spectra of the fluorescence-Raman dual-modal probe with increasing hydrogen sulfide concentration in Example 4;

[0058] Figure 6 Schematic diagram of the linear relationship between the standard concentration of NaHS (H2S) and the intensity of the fluorescence characteristic peak (675±2 cm -1 ) in Example 4;

[0059] Figure 7 Raman spectra of the fluorescence-Raman dual-modal probe with increasing hydrogen sulfide concentration in Example 5;

[0060] Figure 8 Raman spectra of the probes prepared in Example 2 and Comparative Examples 1-3 for hydrogen sulfide. Detailed Embodiments

[0061] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0062] In the following embodiments, unless otherwise specified, the reagents used are commercially available reagents, and the detection means and methods used are conventional detection means and methods in the art.

[0063] The present invention provides a method for preparing a fluorescence-Raman dual-modal probe (a noble metal-MOFs composite material, which means the same thing hereinafter), comprising the following steps:

[0064] (1) Sodium citrate was used as a reducing agent to react with chloroauric acid to synthesize gold nanoparticles of uniform size;

[0065] (2) Then, bovine serum albumin (BSA) was used as a linker and stabilizer to uniformly coat the gold nanoparticles. Silver nitrate solution was added thereto, the pH was adjusted to alkaline with sodium hydroxide solution, and finally sodium borohydride was added for reduction to form gold nanoparticles coated with silver nanoclusters;

[0066] (3) Through a self-assembly method, 4-nitrothiophenol was modified onto the surface of the gold nanoparticles coated with silver nanoclusters. The above-mentioned 4-nitrothiophenol-modified silver nanocluster-gold nanoparticles (AgAuNPS / 4-NTP) were encapsulated in ZIF-8, incubated at room temperature and centrifuged to obtain a fluorescence-Raman dual-mode probe material (AgAuNPs@ZIF-8 / 4-NTP) for detecting hydrogen sulfide.

[0067] In one embodiment of the present invention, in step (1), the gold nanoparticles were prepared by the following method:

[0068] 130 mL of an aqueous solution of HAuCl4 with a concentration of 0.01 wt% was added to a round-bottom flask of a reflux condenser device; by heating under reflux, rapid stirring was carried out and heated to boiling, then 1.5 mL of an aqueous solution of sodium citrate with a concentration of 1 wt% was added until the color changed and then heating was stopped; reflux condensation was maintained and continuous stirring was carried out for 20 - 25 min; centrifugal concentration was carried out at 8000 rpm for 15 min to obtain the gold nanoparticles.

[0069] In one embodiment of the present invention, in step (2), the concentration of the bovine serum albumin (BSA) solution was 0.38 mM, and the volume of bovine serum albumin used was 20 mL; the concentration of the gold nanoparticles was 0.45 nM, and the volume of the gold nanoparticles (sol) used was 500 μL; the concentration of the sodium hydroxide (NaOH) solution for adjusting the system to an alkaline environment was 0.1 M, and the amount used was 3 mL; the concentration of the silver nitrate solution was 0.5 M, the volume of the silver nitrate solution used was 1 mL, the concentration of the NaBH4 solution was 0.01 M, and the volume ratio of the AgNO3 solution to the NaBH4 solution was 1 mL:10 mL.

[0070] In one embodiment of the present invention, the reagent purity of AgNO3 was 99%.

[0071] In one embodiment of the present invention, in step (3), the self-assembly method is as follows: 4-nitrobenzenethiol solution is added to the silver nanocluster-gold nanoparticle solution, incubated at room temperature for 2 h, and then centrifuged; the precipitate is collected and redispersed to obtain 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticles. The solvent method is as follows: An aqueous CTAB solution is added to a 2-methylimidazole solution, and a Zn(NO3)2·6H2O solution and a 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticle solution are sequentially added. After stirring, the mixture is allowed to stand at room temperature for 3 h, incubated at 30 °C for 30 s, and then centrifuged to obtain a fluorescence-Raman dual-modal probe (noble metal-MOFs composite material). Among them: the concentration of the 4-nitrobenzenethiol solution is 0.1 mM, and the dosage is 0.1 mL; the concentration of the aqueous CTAB solution is 1×10 -3 M, the concentration of the 2-methylimidazole solution is 1.32 M, the concentration of the Zn(NO3)2·6H2O solution is 2.4×10 -2 M, the concentration of the 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticle solution is 0.4 nM, and the volumes of the aqueous CTAB solution, 2-methylimidazole solution, Zn(NO3)2·6H2O solution, and 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticle solution are 0.144 mL, 1 mL, 1 mL, and 1 mL in sequence.

[0072] The present invention provides a noble metal-MOFs composite material prepared by the above method, which is a modified silver nanocluster-gold nanoparticle encapsulated in ZIF-8; among them, the modified silver nanocluster-gold nanoparticle is a 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticle; the silver nanocluster-gold nanoparticle is a gold nanoparticle with a silver nanocluster coating on its surface.

[0073] The present invention provides an application of the noble metal-MOFs composite material in detecting hydrogen sulfide molecules, including the following steps:

[0074] (1) Add 1 mL of a NaHS solution with a concentration range of 10 -13 -10 3 M to 2 mL of an aqueous solution of the noble metal-MOFs composite material with a concentration of 0.4 nM, incubate at room temperature for 30 s, and then detect through the fluorescence and SERS dual channels;

[0075] (2) For fluorescence analysis, use a 465 nm excitation light source, measure the emission spectrum with an F97 Pro fluorescence spectrometer, and establish a concentration-fluorescence intensity standard curve;

[0076] (3) During SERS detection, 15 μL of the reaction solution was added dropwise onto the surface of the silicon wafer. After drying at room temperature, Raman spectra were excited and recorded using a 785 nm laser. During data processing, the original spectra were optimized through baseline correction and noise filtering to obtain accurate Raman characteristic peak information for constructing an accurate baseline correction curve.

[0077] In one embodiment of the present invention, SERS detection was performed using a BAC-151B portable Raman spectrophotometer and a diode laser (20 mW) to detect Raman signals.

[0078] During SERS detection, the excitation wavelength was 785 nm, the excitation time was 20 s, and the spectral resolution was 5 cm -1 , and the beam diameter was 10 mm.

[0079] Example 1

[0080] This example provides a AgAuNPs composite noble metal material and its preparation method, including the following steps:

[0081] (1) Preparation of gold nanoparticles:

[0082] 130 mL of 0.01 wt% aqueous chloroauric acid solution was added to a round-bottom flask equipped with a reflux condenser, and it was rapidly stirred and heated to boiling. 1.5 mL of 1 wt% sodium citrate aqueous solution was vigorously stirred and added. It was refluxed and stirred for 20 - 25 min, cooled to room temperature, and a wine-red solution was obtained. It was centrifugally concentrated at 8000 rpm for 15 min to obtain 1 mL of AuNPs colloid with a diameter of 45 - 50 nm ( Figure 1 ).

[0083] (2) In-situ growth method to synthesize gold nanoparticles coated with silver nanoclusters:

[0084] First, 500 mg of bovine serum albumin was dissolved in 20 mL of deionized water. Then, 500 μL of the AuNPs colloid synthesized in (1) above was dispersed into the BSA solution and stirred for 10 min. At this time, the AuNPs concentration was 0.45 nM.

[0085] (3) 1 mL of 0.5 M silver nitrate solution was rapidly added to the BSA aqueous solution containing AuNPs, and 3 mL of 0.1 M NaOH was added to adjust it to alkaline. It was stirred at room temperature for 1.5 h.

[0086] (4) 0.004 g of NaBH4 was weighed and dissolved in 10 mL of deionized water in an ice-water bath, and it was added dropwise to the above solution until the solution turned purple-brownish red to obtain the AgNCs-coated AuNPs composite noble metal (AgAuNPs).

[0087] Example 2

[0088] This embodiment provides a method for preparing a noble metal-MOFs composite material based on a self-assembly strategy, including the following steps:

[0089] (1) First, take 10 mL of the previously prepared AgAuNPs solution with a concentration of 0.45 nM, and add 0.1 mL of a 4-nitrobenzenethiol solution with a concentration of 0.1 mM thereto;

[0090] (2) Incubate the mixture at room temperature for 2 h to ensure that 4-nitrobenzenethiol is fully bound to AgAuNPs. After incubation, remove the unbound excess 4-nitrobenzenethiol by centrifugation (rotation speed: 8000 rpm, duration: 5 min);

[0091] (3) Collect the precipitate deposited at the bottom and redisperse it in 5 mL of deionized water to obtain a 4-nitrobenzenethiol-functionalized AgAuNPs solution (AgAuNPs / 4-NTP). Adjust the concentration of this solution to 0.4 nM and store it at 4 °C;

[0092] (4) Inject 0.144 mL of an aqueous CTAB solution with a concentration of 1×10 -3 M into 1 mL of a 2-methylimidazole solution with a concentration of 1.32 M, and then perform magnetic stirring for 5 min. Sequentially add 1 mL of a Zn(NO3)2·6H2O solution with a concentration of 2.4×10 -2 M and 1 mL of an AgAuNPs / 4-NTP solution with a concentration of 0.4 nM, stir for 5 min, and let it stand at room temperature for 3 h;

[0093] (5) After incubation, perform centrifugation at a rotation speed of 5000 rpm for 5 min. Wash the precipitate three times repeatedly with 10 mL of methanol to obtain a noble metal-MOFs composite material (AgAuNPs@ZIF-8 / 4-NTP), and then redisperse it in 5 mL of methanol for storage. From the TEM image ( Figure 2 )), the morphology of the synthesized AgAuNPs@ZIF-8 / 4-NTP in this scheme can be clearly seen.

[0094] Example 3

[0095] This embodiment provides a qualitative detection of hydrogen sulfide using the noble metal-MOFs composite material prepared in Example 2, including the following steps:

[0096] (1) Place 3 mL of the fluorescence-Raman dual-modal probe prepared in Example 2 in a quartz cuvette, and sequentially add 0.1 μmol / L NaHS (as a hydrogen sulfide source) and different interfering substances dissolved therein (Na + , K + , Zn2+ , Cl - , Cys) solution, and observed at 465nm; Figure 3 As shown, hydrogen sulfide weakens the fluorescence, while other ions have no weakening effect, so hydrogen sulfide can be qualitatively monitored and analyzed from the fluorescence channel;

[0097] (2) 5 μL of 0.1 μmol / L different interfering substance solutions (F - Br - 、CH3COO - , ) was added to the noble metal-MOFs composite material prepared in Example 2 and mixed evenly, then dropped on a silicon wafer, and after collecting 5 points from each sample to measure the SERS signal, 5 μL of 0.1 μmol / L NaHS was added, mixed evenly, and 5 points were collected to measure the SERS signal, all of which were background-subtracted;

[0098] (3) A BAC-151B portable Raman spectrophotometer and a diode laser (20 mW) were used to detect Raman signals with an excitation wavelength of 785 nm and an excitation time of 20 s to obtain the SERS spectrum of the sample.

[0099] The Raman spectrum peak is 1565 cm -1 and 1591cm -1 As the characteristic peak for determining hydrogen sulfide, hydrogen sulfide reduces the nitro group, such as Figure 4 As shown, the Raman characteristic signal is from 1565±2cm -1 To 1591±2cm -1 The characteristic peak positions of other ions do not change, so hydrogen sulfide can be qualitatively detected and analyzed by Raman channel.

[0100] Example 4

[0101] This embodiment provides a method for quantitative fluorescence detection of hydrogen sulfide by the noble metal-MOFs composite material prepared in Example 2, comprising the following steps:

[0102] (1) 3 mL of noble metal-MOFs composite material was placed in multiple quartz cuvettes, and equal amounts of concentrations of 10 -13 -10 -3 NaHS solutions with different mol / L.

[0103] (2) Fluorescence quantitative analysis uses a 465 nm excitation light source and is measured by a F97 Pro fluorescence spectrometer with a concentration between 10 -13 -10 -3 NaHS solutions with different mol / L ( Figure 5)。

[0104] (3) As the concentration of NaHS increases, the fluorescence gradually weakens. According to the fluorescence intensities of the noble metal-MOFs composite materials under different standard NaHS solution concentrations, a standard curve is plotted with the logarithm value of the standard NaHS solution concentration as the abscissa and the corresponding fluorescence intensity as the ordinate.

[0105] Select 675±2 cm -1 As the intensity of the corresponding fluorescence peak combined with the linear curve can be used to calculate the content of H2S. According to the linear relationship y = 62.42 - 108.43x between the concentration of hydrogen sulfide (1×10 -13 ~10 -3 M) and the fluorescence signal intensity, R 2 =0.984( Figure 6 );The detection limit (LOD) is calculated according to the ratio of three times the measured blank standard deviation (δ) to the slope (k) of the linear curve, that is, DL = 3δ / k. The detection limit of hydrogen sulfide can be obtained as: 1×10 -7 μM.

[0106] Example 5

[0107] This example provides the Raman quantitative detection of hydrogen sulfide by the noble metal-MOFs composite material prepared in Example 2, including the following steps:

[0108] (1) Sequentially add 5 μL of NaHS solutions with different concentrations (10 -13 -10 -3 mol / L) to the AgAuNPs@ZIF-8 / 4-NTP probe, mix evenly, then drop it on a silicon wafer, and measure the SERS signal by collecting 5 points from each sample;

[0109] (2) Use a BAC-151B portable Raman spectrometer and a diode laser (20 mW) to detect the Raman signal. The excitation wavelength is 785 nm and the excitation time is 20 s to obtain the SERS spectrum of the sample.

[0110] Using the Raman spectral peaks at 1565 cm -1 and 1591 cm -1 as the characteristic peaks for determining hydrogen sulfide. As the concentration of NaHS gradually increases (1×10 -13 ~10 -3 M), the Raman shift at 1565±2 cm -1 in the Raman spectrum changes from 1565±2 cm -1 to 1591±2 cm Figure 7 ) during the process of increasing the concentration of NaHS.

[0111] Comparative Example 1

[0112] Gold nanoparticles (AuNPs) were obtained according to the same experimental protocol as in Example 1; the remaining preparation parameters (such as growth time, solution concentration) were the same as those in Examples 1 and 2.

[0113] Comparative Example 2

[0114] AgNCs-coated AuNPs composite noble metal (AgAuNPs) was obtained according to the same experimental protocol as in Example 1; the remaining preparation parameters (such as growth time, solution concentration) were the same as those in Examples 1 and 2.

[0115] Comparative Example 3

[0116] (3) A composite noble metal solution of AgAuNPs@ZIF-8 encapsulated with ZIF-8 was obtained according to the same experimental protocol as in Example 2; the remaining preparation parameters (such as growth time, solution concentration) were the same as those in Examples 1 and 2.

[0117] AuNPs, AgAuNPs, AgAuNPs@ZIF-8, and AgAuNPs@ZIF-8 / 4-NTP prepared in Comparative Examples 1-3 and Example 2 were used as SERS substrates for comparison. A BAC-151B portable Raman spectrophotometer and a diode laser (20 mW) were used to detect Raman signals. The excitation wavelength was 785 nm, and the excitation time was 20 s to obtain the SERS spectra of the samples.

[0118] AuNPs, AgAuNPs, AgAuNPs@ZIF-8: In the presence of hydrogen sulfide, only a weak broad-spectrum signal caused by H2S adsorbed on the surface of AuNPs was observed, and there was no specific peak change (ΔI < 10%) ( Figure 8 curves a-c)

[0119] AgAuNPs@ZIF-8 / 4-NTP: In the presence of hydrogen sulfide, the 1565 cm -1 peak disappeared, and the 1591 cm -1 peak was significantly enhanced ( Figure 8 curves d-e), indicating the complete conversion of nitro to amino.

[0120] If the Raman probe molecule 4-NTP modification is lacking, the probe only depends on the physical adsorption of H2S on the surface of AuNPs, and the SERS signal has no specific change, and the detection limit and anti-interference ability are significantly deteriorated.

[0121] By comparing and analyzing the performance of AuNPs, AgAuNPs, and AgAuNPs@ZIF-8 for hydrogen sulfide detection, the core role of 4-NTP is shown:

[0122] (1) Specific reaction site: The nitro group (-NO2) of 4-NTP provides a chemoselective target for H2S, ensuring that the reaction is triggered only in the presence of H2S;

[0123] (2) SERS signal amplification: After the nitro group is reduced to an amino group, the molecular polarizability increases significantly, and the Raman signal is amplified through the local surface plasmon resonance (LSPR) effect;

[0124] (3) Synergistic ZIF-8 enrichment and protection: The pores of ZIF-8 selectively enrich H2S, enhancing the reaction rate; at the same time, it protects 4-NTP from being covered by biomolecules, maintaining long-term stability.

[0125] (4) Synergistic ZIF-8 confinement effect: The nano-confinement environment of ZIF-8 enhances the local concentration of reactants and optimizes the reaction kinetics.

[0126] Through comparative experiments and mechanism analysis, it is found that 4-NTP is the core feature for the probe of the present invention to achieve ultra-high sensitivity, specificity, and reliability. It can fully prove that its synergistic effect with the ZIF-8 shell and AuAgNCs is the core creative feature for the technical solution of the present invention to achieve highly sensitive and highly stable dual-mode detection.

[0127] In summary, the present invention provides a novel core-shell fluorescence-Raman dual-mode sensing nanoprobe (AgAuNPs@ZIF-8 / 4-NTP) and uses this probe to quantitatively and qualitatively detect and analyze hydrogen sulfide; the present invention first prepares the AgAuNPs@ZIF-8 / 4-NTP dual-mode probe through a self-assembly strategy, and the working principle of this dual-sensing strategy is based on the precipitation reaction of hydrogen sulfide with silver nanoclusters (Ag + ) resulting in a decrease in fluorescence intensity. At the same time, hydrogen sulfide undergoes a reduction reaction with the nitro group on the benzene ring of 4-nitrothiophenol, generating a new characteristic peak at 1591 cm -1 in the Raman spectrum. In addition, the introduction of the ZIF-8 metal-organic framework effectively enriches hydrogen sulfide and significantly enhances the detection signal. Therefore, based on the dual-mode verification mechanism, this probe significantly reduces the misjudgment probability through signal complementarity, greatly improves the anti-interference ability, and supports real-time in-situ monitoring by portable devices, providing a new strategy for hydrogen sulfide detection with high selectivity, sensitivity, and convenience.

[0128] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A fluorescence-Raman dual-mode probe for hydrogen sulfide detection, characterized in that, The described fluorescence-Raman dual-modal probe is composed of modified silver nanocluster-gold nanoparticles encapsulated in ZIF-8; Among them, The modified silver nanocluster-gold nanoparticles are 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticles; The silver nanocluster-gold nanoparticles are gold nanoparticles coated with a silver nanocluster layer on the surface.

2. A preparation method of the fluorescence-Raman dual-modal probe for hydrogen sulfide detection as described in claim 1, characterized in that, It includes the following steps: (1) Synthesis of gold nanoparticles by reduction method: Using sodium citrate aqueous solution as a reducing agent to react with chloroauric acid solution to synthesize gold nanoparticles; (2) In-situ growth method for synthesizing silver nanocluster-gold nanoparticles: Using bovine serum albumin solution as a linker and stabilizer to uniformly coat gold nanoparticles, then adding silver nitrate solution, adjusting the pH to alkaline and adding sodium borohydride for reduction to form gold nanoparticles coated with a silver nanocluster layer on the surface; (3) Obtaining the fluorescence-Raman dual-modal probe by self-assembly method: Modifying 4-nitrobenzenethiol onto the surface of silver nanocluster-gold nanoparticles by self-assembly method, and then encapsulating it in ZIF-8 by solvent method.

3. The preparation method of a fluorescence-Raman dual-modal probe for hydrogen sulfide detection according to claim 2, wherein In step (1), after heating the chloroauric acid solution to boiling, add sodium citrate aqueous solution, and stop heating after color change to obtain gold nanoparticle colloid; The concentration of the sodium citrate aqueous solution is 1 wt%, the concentration of the chloroauric acid solution is 0.01 wt%, and the volume ratio of the sodium citrate aqueous solution to the chloroauric acid solution is 1.5:

130.

4. The preparation method of a fluorescence-Raman dual-mode probe for hydrogen sulfide detection according to claim 2, characterized in that, In step (2), The concentration of the bovine serum albumin solution is 0.38 mM, the concentration of the gold nanoparticles is 0.45 nM, and the volume ratio of the bovine serum albumin solution to the gold nanoparticles is 20 mL:500 μL; The concentration of the silver nitrate solution is 0.5 M, and the volume ratio of the silver nitrate solution to the gold nanoparticles is 1 mL:500 μL.

5. The preparation method of a fluorescence-Raman dual-modal probe for hydrogen sulfide detection according to claim 2, wherein In step (3), the self-assembly method includes the following steps: Add 4-nitrobenzenethiol solution to the silver nanocluster-gold nanoparticle solution, incubate and then centrifuge; collect the precipitate and redisperse it to obtain 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticles.

6. The preparation method of a fluorescence-Raman dual-modal probe for hydrogen sulfide detection according to claim 5, characterized in that, The concentration of the silver nanocluster-gold nanoparticle solution is 0.45 nM, the concentration of the 4-nitrobenzenethiol solution is 0.1 mM, and the volume ratio of the silver nanocluster-gold nanoparticle solution to the 4-nitrobenzenethiol solution is 10 mL:0.1 mL; The incubation is carried out at room temperature for 2 hours.

7. The preparation method of a fluorescence-Raman dual-modal probe for hydrogen sulfide detection according to claim 2, characterized in that, In step (3), the solvent method includes the following steps: Add cetyltrimethylammonium bromide aqueous solution to 2-methylimidazole solution, sequentially add zinc nitrate hexahydrate solution and 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticle solution, stir and then let stand, incubate and then centrifuge to obtain the fluorescence-Raman dual-modal probe.

8. The preparation method of a fluorescence-Raman dual-modal probe for hydrogen sulfide detection according to claim 7, characterized in that, The concentration of the cetyltrimethylammonium bromide aqueous solution is 1×10 -3 M, the concentration of the 2-methylimidazole solution is 1.32 M, the concentration of the zinc nitrate hexahydrate solution is 2.4×10 -2 M, and the concentration of the 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticle solution is 0.4 nM. The volume ratio of the cetyltrimethylammonium bromide aqueous solution, the 2-methylimidazole solution, the zinc nitrate hexahydrate solution, and the 4-nitrobenzenethiol-modified silver nanocluster-gold nanoparticle solution is 0.144 mL: 1 mL: 1 mL: 1 mL; The standing is carried out at room temperature for 3 h; The incubation is carried out at 30 °C for 30 s.

9. Application of a fluorescence-Raman dual-modal probe for hydrogen sulfide detection as described in claim 1 in the technical field of hydrogen sulfide detection.

10. The application according to claim 9, wherein Mix the aqueous solution containing the fluorescence-Raman dual-modal probe with sodium hydrosulfide solution for reaction, and perform dual-modal detection after the reaction; The dual-modal detection includes fluorescence analysis and SERS detection; The fluorescence analysis uses a 465 nm excitation light source; The SERS detection uses a 785 nm laser to excite for 20 s.

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