Cyanide ratio response Raman probe as well as preparation method and application thereof

Abstract

The invention discloses a cyanide ratio response Raman probe and a preparation method and application thereof.The probe is composed of a gold nanostar substrate and cyanide ion response Raman reporter molecules connected through gold-sulfur bonds, and the reporter molecules are connected with 1, 1, 2, 3, 4-tetracarboxylic acid through ethylene bridges. 2, 2-trimethyl-3-ethyl-1H-benzoindole and N-ethylcarbazole-3-formaldehyde are used as recognition units, and can specifically react with CN <->. The probe adopts a ratio detection strategy, takes a 1507cm <-1 > peak as an internal reference and a 2105cm <-1 > peak as a response signal, is linearly correlated with the CN <-> concentration in a range of 0.1-10 mu M (R2 is equal to 0.9902), the detection limit reaches 0.1 mu M, and the sensitivity is improved by more than 10 times compared with that of a traditional SERS (Surface Enhanced Raman Scattering) method. The probe is high in anti-interference performance, response to common anions, thiol and active oxygen can be ignored, signal change to CN <-> reaches 15.5 times, single detection only needs 3 minutes, and the probe is suitable for rapid and high-selectivity quantitative detection of cyanide in a complex environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of analytical chemistry, in particular to a cyanide ratio response Raman probe and a preparation method and application thereof. BACKGROUND

[0002] Cyanide is a highly toxic substance, which widely exists in industrial production and environmental samples. It is of great significance to realize rapid, high-sensitivity and accurate quantitative detection of cyanide in environmental monitoring, food safety and public safety emergency response.

[0003] Currently, there are three main methods for cyanide detection: (1) visual colorimetric method, which relies on detection kits and other detection equipment, uses cyanide to generate colored substances with certain reagents (such as zirconium alizarin sulfonic acid, dioctylcinic acid), and determines the cyanide content according to the color depth; (2) spectrophotometry, which is a method in which CN - reacts with certain reagents (such as isonicotinic acid-barbituric acid, isonicotinic acid-pyrazolone), and the absorbance at the maximum absorption wavelength of the solution after the reaction is proportional to the concentration within a certain range, which conforms to the Lambert-Beer law; (3) gas chromatography, which mainly detects cyanide and part of metal cyanide complexes after derivatization by gas chromatography / electron capture detector, and is widely used in the detection of cyanide in complex samples, especially biological samples, in clinical and forensic medicine. Among the above three methods, the visual colorimetric method and the spectrophotometry have significant visual effect, but the sensitivity is poor (0.01-1mg / L), easy to be secondarily contaminated, and the specificity is insufficient, which is easily disturbed by complex biological matrix. Although gas chromatography is the "gold standard" for cyanide detection, it can accurately quantify, but the method is complex in pretreatment operation, requires professional technical personnel to operate and analyze, and takes a long time (~60min), and the method relies on non-portable large instruments, which cannot be used for real-time and on-site detection of cyanide, which is not conducive to large-scale routine detection and rapid response to public health emergencies. Therefore, rapid identification and accurate quantification are the problems to be solved in the current cyanide detection.

[0004] Raman scattering refers to the phenomenon that the frequency of scattered light changes after the non-elastic collision of photons on the surface of an object. Surface-enhanced Raman scattering (SERS) refers to the phenomenon that the Raman signal is greatly enhanced due to the influence of the local electric field of the rough surface of noble metal on the molecules to be detected (10 6 -10 10 times, and the detection limit is as low as 10 -9 -10 -15M) Compared with Raman spectrum, SERS has the characteristics of high sensitivity, strong specificity (fingerprint), strong signal stability, etc., and is widely used in biological imaging, medical diagnosis, forensic science and other fields, and has unique advantages in on-site detection of poisons. At present, there are related reports on cyanide detection based on SERS technology. However, the current strategy has the problems of low detection sensitivity and unstable quantification, which cannot meet the requirements of low concentration cyanide detection and accurate quantitative analysis.

[0005] Therefore, there is a lack of a rapid detection method for cyanide with high sensitivity, high specificity, anti-interference and accurate quantification in the prior art, which seriously restricts its application in on-site rapid detection scenarios. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art and provide a cyanide ratio response Raman probe and a preparation method and application thereof.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0008] The first aspect is to provide a cyanide ratio response Raman probe, which is composed of a gold nano substrate and a cyanide ion response Raman reporter molecule, and the structure is shown in the following formula V:

[0009]

[0010] Among them, A is a gold nano substrate;

[0011] X is a cyanide ion response Raman reporter molecule, and its structure is shown in formula I-a;

[0012]

[0013] X is connected to the gold surface of A through a gold-sulfur covalent bond;

[0014] A is a substrate for enhancing Raman signals, which is used to produce an electric field enhancement effect to enhance the Raman signals of X; X is used to realize the quantitative determination of cyanide ions.

[0015] Further, the A is a gold nano star, which has a plurality of sharp ends and branch structures, and the particle size is 20-150 nm; preferably 60±10 nm.

[0016] Further, the molar ratio of X to A is 5×10 3 :1-3×10 4 :1; preferably 1×10 4 :1.

[0017] Further, the Raman spectrum formed by the substance shown in formula V has one or more characteristic peaks: 585cm -1, 717 cm -1 , 943 cm -1 , 1197 cm -1 , 1301 cm -1 , 1448 cm -1 , 1507 cm -1 , 1564 cm -1 , 2105 cm -1 .

[0018] The second aspect is to provide a preparation method of the cyanide ratio-responsive Raman probe, comprising the following steps:

[0019] S1, preparing a cyanide-responsive Raman reporter I-a;

[0020] S2, preparing a gold nanostar substrate by a seed growth method;

[0021] S3, performing an assembly reaction on the reporter I-a prepared in step S1 and the gold nanostar substrate prepared in step S2, so that the reporter I-a is connected to the surface of the gold nanostar substrate through a gold-sulfur covalent bond, thereby obtaining the cyanide ratio-responsive Raman probe.

[0022] Further, the step S1 of preparing the cyanide-responsive Raman reporter I-a comprises:

[0023] S1-a: dissolving 1,1,2-trimethyl-3-ethyl-1H-benzoindole and N-ethylcarbazole-3-formaldehyde in an organic solvent, and performing a condensation reaction by heating reflux, and after the reaction is completed, performing filtration, washing, and drying to obtain an intermediate I-3;

[0024] S1-b: performing an esterification reaction on the intermediate I-3 and lipoic acid in the presence of dicyclohexyl carbodiimide and dimethyl amino pyridine in an organic solvent in the dark, and after the reaction is completed, performing spin drying and chromatographic purification to obtain the reporter I-a.

[0025] Further, the step S2 of preparing the gold nanostar substrate by the seed growth method comprises:

[0026] S2-a: reducing a first aqueous gold chloride solution with a sodium citrate solution under heating and boiling conditions, stirring the reaction until gold seeds are generated, and obtaining a gold seed solution;

[0027] S2-b: under acidic conditions and stirring, sequentially adding the gold seed solution, an aqueous silver nitrate solution, and an aqueous ascorbic acid solution to a second aqueous gold chloride solution, and generating a gold nanostar solution by reaction.

[0028] Further, in the step S3, the reaction is performed under stirring at room temperature, and the reaction time is 20-50 minutes.

[0029] The third aspect provides application of the cyanide ratio-responsive Raman probe in detection of cyanide, wherein the concentration (calculated as CN-) of the cyanide is 0.1 μM to 10 μM.

[0030] Compared with the prior art, the probe has the following technical effects:

[0031] The probe uses ethylene bridge to connect the electron acceptor 1,1,2-trimethyl-3-ethyl-1H-benzindole and the electron donor N-ethylcarbazole-3-formaldehyde as the specific recognition unit of CN-, and the CN- nucleophilically attacks the C≡N triple bond formed by the ethylene bridge in the probe molecule. The chemical reaction between the unit and the CN- has high specificity. In the presence of 10 times the concentration of common anions (such as Cl - , F - , SO4 2- , NO3 - , HS - , CO3 2- , HCO3 - ), biological thiols (GSH and Cys) and active oxygen (H2O2), the change rate of the SERS signal (I 2105 ) of the probe is less than 1 times, while the change rate of the response signal of the same concentration of CN- is as high as 15.5 times. This fully proves that the probe has excellent anti-interference ability and high selectivity in a complex environmental matrix, and effectively solves the technical problem that the existing fluorescence or colorimetric method is easily interfered by other ions and causes false positives.

[0032] The probe adopts a ratio detection strategy, and uses the Raman peak at 1507 cm -1 as an inert reference peak and the Raman peak at 2105 cm -1 as a specific response peak. In the CN- concentration range of 0.1 μM to 10 μM, the ratio signal (I 1507 / I 2105 ) and the CN- concentration present a good linear relationship (R 2 = 0.9902). The detection limit (LOD) of the method is as low as 0.1 μM (signal-to-noise ratio S / N = 3), and the sensitivity is improved by more than 10 times compared with the traditional direct SERS detection method (the detection limit is usually 1-10 μM).

[0033] After the probe reacts with CN - , the Raman characteristic peak at 2105 cm -1 , which belongs to the cyanogen C≡N stretching vibration, appears, and the peak intensity is significantly enhanced with the increase of the CN - concentration, while the Raman peak (peak 1507 cm -1 ) belonging to the stretching vibration of the aromatic heterocyclic C-C skeleton is not affected by the CN -The peak intensity remained relatively stable after the action. When the concentration of the probe was unchanged, the CN - When the concentration value increased from 0.1 μM to 10 μM, the characteristic double-peak intensity ratio (I 1507 / I 2105 ) of the Raman signal intensity ratio decreased from 9.43 to 1.15, with a change of more than 8 times. This effect is directly due to the ratio design in the technical solution, which realizes the accurate quantification of trace cyanide in the environment.

[0034] The reaction of the probe of the present application with CN- is rapid, and a single detection can be completed within 3 minutes. In comparison, the reaction time of the commercially available cyanide rapid detection kit based on visual colorimetry and spectrophotometry is usually not less than 5 minutes, and some chromatographic methods requiring complex extraction or derivatization steps usually require more than 30 minutes. This fast response characteristic makes the present application particularly suitable for the on-site rapid screening of cyanide. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The cyanide ratio response Raman probe of the present application responds to the concentration fluctuation of cyanide ions; wherein A is the SERS spectrum under the condition of gradient concentration of cyanide ion solution; B is the SERS peak intensity ratio (I 1507 / I 2105 ) - cyanide ion concentration working curve (0.1 μM - 10 μM).

[0036] Figure 2 The cyanide ratio response Raman probe of the present application is applied to the rapid detection of cyanide in wax pills; wherein A is a photo of suspicious wax pills; B is the SERS spectrum after the ratio type SERS probe acts on the pretreated sample, and a carbon-nitrogen triple bond characteristic peak appears at a Raman shift of 2105 cm -1 .

[0037] Figure 3 The response kinetics of the cyanide ratio response Raman probe of the present application.

[0038] Figure 4 The cyanide ratio response Raman probe of the present application is applied to the rapid detection of cyanide in wax pills; wherein A is a photo of suspicious wax pills; B is the SERS spectrum after the ratio type SERS probe acts on the pretreated sample, and a carbon-nitrogen triple bond characteristic peak appears at a Raman shift of 2105 cm - and 10 times the concentration of the interferent; B is the response column chart of the probe solution and CN - after the action, and then other interferents are added.

[0039] Figure 5 The transmission electron microscope photo of the cyanide ratio response Raman probe of the present application. DETAILED DESCRIPTION

[0040] The present application aims to solve the technical bottlenecks of the existing cyanide detection method, such as weak anti-interference ability in complex matrix, poor quantitative accuracy and complicated pretreatment, so as to realize rapid, high-sensitivity and high-selectivity analysis of trace cyanide in complex samples such as environmental water samples and suspicious seizures.

[0041] In view of the problem of insufficient sensitivity, a SERS detection system based on gold nanostar is constructed to realize sensitive detection of cyanide. Gold nanostars with sharp tips can generate a large number of electromagnetic hot spots, and can provide strong SERS enhancement effect with the help of near-field plasmonic coupling effect; in addition, a large number of gaps between the branches of the nanostar can generate a large number of "hot spots", realizing amplification of Raman signals. Further adjustment of the plasmonic resonance frequency of the gold nanostar substrate, design and modification of a near-infrared absorption reporter molecule, selection of a wavelength-matched excitation light source, and use of surface-enhanced resonance Raman can realize high-sensitivity detection of the detected substance at the picomolar (pM) level.

[0042] Accurate quantification is the second challenge of SERS for cyanide detection. The ratio detection technology uses the ratio of two or more detection signals that do not interfere with each other as the output instead of the absolute value of a single signal, which can overcome the influence of imaging focal length, substrate state and probe concentration and other parameters unrelated to the target on the intensity-type Raman probe, thereby greatly enhancing the reproducibility of the detection result and realizing accurate and quantitative detection of the detected substance. In addition, the range of wave number less than 1800 cm -1 in the Raman spectrum is called "molecular fingerprint region", because most substances will have specific spectral information in this region, just like a person's fingerprint; and 1800-2800 cm -1 is the "Raman silent zone", in which most substances, especially biological samples, will not produce Raman signals. Therefore, using Raman molecules that can peak in the "silent zone" can reduce the interference of exogenous substances, especially complex matrix, on the detected sample, to improve the accuracy and reproducibility of the system detection.

[0043] The present application will be further described below in conjunction with the drawings and specific embodiments, but is not limited by the embodiments and features in the embodiments can be combined with each other without conflict.

[0044] Example 1 Synthesis of cyanide-responsive Raman reporter molecule I-a

[0045]

[0046] After 3.65 g of 1,1,2-trimethyl-3-ethyl-1H-benzoindole (I-1, 10 mmol) and 2.33 g of N-ethylcarbazole-3-carboxaldehyde (I-2, 10 mmol) were uniformly mixed, they were dissolved in 100 mL of anhydrous ethanol, and the reaction was heated to reflux at 85°C for 5 h. After the reaction was completed and cooled to room temperature, the solid precipitate was collected by filtration, the crude product was washed with ice-ethanol, and dried in a vacuum drying box overnight to obtain the dark red target product I-3.

[0047] Substance I-3 (0.18 mmol, 1.0 eq) was dissolved in 5.0 mL of dichloromethane with dimethylaminopyridine (DMAP, 0.55 mmol, 3.0 eq), lipoic acid (0.18 mmol, 1.0 eq), and dicyclohexyl carbodiimide (DCC, 0.55 mmol, 3.0 eq). The reaction was carried out at room temperature for 18 h in the dark. After the reaction system was dried with a rotary evaporator, 1 mL of a 2:1 mixture of dichloromethane and methanol was used to obtain a crude product solution for purification. Finally, the crude product solution was further separated and purified using silica gel column chromatography to obtain purple-red substance I-a.

[0048] The specific conditions for silica gel column chromatography separation and purification are as follows:

[0049] Silica gel column: 200-300 mesh silica gel was packed into a silica gel column with an inner diameter of 40 mm and a length of 300 mm;

[0050] Elution conditions: The crude product solution to be purified was uniformly loaded, and then eluted with 200 mL of dichloromethane, 1000 mL of a dichloromethane and methanol mixture (CH2Cl2:MEOH = 20:1, V:V), 1000 mL of a dichloromethane and methanol mixture (CH2Cl2:MEOH = 10:1, V:V), and 600 mL of a dichloromethane and methanol mixture (CH2Cl2:MEOH = 8:1, V:V) at a speed of about 50 mL / min.

[0051] 1H NMR (600MHz, DMSO-d6) δ: 9.15 (s, 1H), 8.84 (d, J = 16.0 Hz, 1H), 8.45 (dd, J = 8.5, 6. 0Hz,2H),8.30(d,J=9.0Hz,2H),8.22(d,J=8.2Hz,1H),8.13(d,J=8.9Hz,1H),7.8 8(d,J=8.7Hz,1H),7.84(d,J=6.6Hz,1H),7.81(d,J=6.5Hz,1H),7.75(d,J=8.2Hz ,1H),7.72(t,J=7.5Hz,1H),7.59(t,J=7.8Hz,1H),7.39(t,J=7.4Hz,1H),5.22(d ,J=5.3Hz,2H),4.65(t,J=5.0Hz,2H),4.57(q,J=7.2Hz,2H),3.06(dt,J=12.3,6. 2Hz,1H),2.83(t,J=6.5Hz,2H),2.09(s,6H),2.04(td,J=7.6,3.4Hz,2H),1.95(d q,J=12.4,6.2Hz,1H),1.39(t,J=7.2Hz,3H),1.33(dq,J=13.3,6.9Hz,1H),1.16– 1.12(m,2H),1.07–1.00(m,1H),1.00–0.93(m,1H),0.87(dq,J=15.3,7.8Hz,2H).

[0052] ESI-MS calc.for C 40 H 43 N₂O₂S₂[M+H] + :647.2760, found 647.2775.

[0053] Example 2 Synthesis of a cyanide ratio-responsive Raman probe (substance shown in Formula V)

[0054] Prepare 200 mL of a 1.0 mM gold chloride aqueous solution (HAuCl4) using ultrapure water and heat it to boiling. Quickly add 30 mL of a 1% (w / v) sodium citrate aqueous solution to the 200 mL of the boiled gold chloride aqueous solution. Stir at 1000 rpm for 15 min while boiling, and cool to room temperature to obtain a gold seed solution with a particle size of 10-15 nm and a concentration of 0.01 nmol / L.

[0055] Prepare 200 mL of 0.25 mM gold chloride aqueous solution using ultrapure water. Adjust the system to acidity by adding approximately 1 mL of pH 1 hydrochloric acid solution at 650 rpm, then add 4 mL of the aforementioned gold seed solution. Adjust the stirring speed to 1500 rpm, and simultaneously add 2.0 mL of ultrapure silver nitrate aqueous solution (3.0 mmol / L) and 1.0 mL of ultrapure ascorbic acid aqueous solution (100 mmol / L). Continue stirring for 30 s to obtain a gold nanostar solution with a particle size of 60 ± 10 nm.

[0056] A 1 mol / L solution of Ia was prepared using methanol as the solvent.

[0057] At a rotation speed of 650 rpm, 20 μL of Ia solution was added to the above gold nanostar solution, and the reaction was carried out at room temperature for 30 min to obtain the probe solution.

[0058] The morphology of the probe was characterized by transmission electron microscopy. 10 μL of the probe solution was added to a copper grid and dried under an infrared lamp. Under the transmission electron microscope, it showed a branched, uniformly dispersed star-shaped structure. Figure 5 ).

[0059] The Raman spectrum of the probe was acquired using a handheld Raman spectrometer. 0.2 mL of the probe solution (1 nmol / L) was placed on tin foil and irradiated with an excitation wavelength of 785 nm. The acquisition time was set to 200 ms. The characteristic Raman peak assignment information of the probe is shown in Table 1 below.

[0060] Table 1

[0061]

[0062]

[0063] Example 3 Probe to CN - Ratio response capability test

[0064] A handheld Raman spectrometer was used to collect probes for different CNs. - Raman spectra of the response. Take 1 mL of a 10 nmol / L probe solution and add 10 μL of CN at gradient concentrations. - Aqueous solution. After thorough mixing, incubate at room temperature for 3 min, and measure the Raman spectrum of the probe at an excitation wavelength of 785 nm. Response CN - The Raman characteristic peak assignment information is shown in Table 2 below.

[0065] Table 2

[0066]

[0067] Table 3 Different CN -Characteristic peak intensity of the probe at concentration

[0068]

[0069]

[0070] As shown in Table 3, the 2105 cm⁻¹ bond, which belongs to the carbon-nitrogen triple bond, -1 Located in CN - After the action, characteristic peaks begin to appear, and the peak intensity gradually increases, while the Raman peak (peak 1507 cm⁻¹) is attributed to the stretching vibration of the aromatic heterocyclic CC skeleton. -1 (location) in CN - After the effect, the peak intensity remained relatively stable overall. Compared to CN... - Under the condition of a concentration of 0, the probe is at a concentration of 0.1 μM CN. - The characteristic peaks of the carbon-nitrogen triple bond can appear under these conditions. With a constant probe concentration, CN... - When the concentration increases from 0.1 μM to 10 μM, the characteristic bimodal ratio (I) Peak2 / I Peak1 The Raman signal intensity ratio decreased from 9.43 to 1.25, a change of more than 8 times. (The last sentence appears to be incomplete and possibly refers to a different topic.) Peak1 / I Peak2 Signal strength ratio and CN - Plotting concentration values ​​within a certain CN range - Within the concentration range, I Peak1 / I Peak2 The value of CN - The concentrations are positively correlated. (From...) Figure 1 It can be seen that within the CN- concentration range of 0.1 μM to 10 μM, the ratio signal (I) 1507 / I 2105 The concentration of ) showed a good linear relationship with CN- concentration (R 2 =0.9902). The method's limit of detection (LOD) is as low as 0.1 μM (signal-to-noise ratio S / N = 3).

[0071] Example 4: Response kinetics experiment of cyanide ratio-responsive Raman probe

[0072] Transfer 1 mL of a 10 nmol / L probe solution and add 10 μL of a 2 μg / mL CN solution. - Aqueous solution. Using a handheld Raman spectrometer (Ocean Optics QE65 Pro, excitation wavelength 785nm, laser power 20mW, integration time 500ms), spot scanning was performed on the probe solution in relation to CN. - Starting from the 0s mark of the aqueous solution mixing, a 5s acquisition time interval was set to acquire the Raman spectrum of the mixed solution.

[0073] During spectral data processing, the peak at 2105 cm⁻¹ was selected before and after the probe molecule reacted with cyanide ions. -1 The change in peak intensity of the characteristic peak. Plotting reaction time on the x-axis, at 2105 cm⁻¹. -1 The peak area of ​​the characteristic peak was plotted on the ordinate to obtain the CN-response kinetic curve of the probe. Results ( Figure 3 The results showed that after the probe interacted with CN-, the velocity reached 2105 cm⁻¹. -1 The intensity of the characteristic peak gradually increases and reaches a stable plateau at about 150s.

[0074] Example 5 Interference Experiment

[0075] To verify the specificity of the probe's response to cyanide (CN-), the effects of various potential interfering substances were systematically investigated. Samples containing only the probe solution served as blank controls; 1 mL of a 10 nmol / L probe solution was transferred, and 10 μL of a 100 μM CN- solution was added. - An aqueous solution was used as a positive control; simultaneously, 1.0 mM Cl solutions were prepared using deionized water. - F - SO4 2- NO3 - HS - CO3 2- HCO3 - 1 mL of the probe working solution was transferred to each of the following solutions: biothiols (GSH and Cys) and reactive oxygen species (H2O2). The solutions were then incubated at room temperature for 3 min. Raman spectra were then acquired using a handheld Raman spectrometer (OceanOptics QE65 Pro, excitation wavelength 785 nm, laser power 20 mW, integration time 500 ms).

[0076] During spectral data processing, the 2105 cm⁻¹ value was selected after the probe molecule reacted with cyanide ions. -1 The peak intensities of the characteristic peaks were statistically calculated. Experimental results ( Figure 4 The display shows that the SERS signal (I) of each interference group 2105 The change rate of the positive control group was less than 1, while the change rate of the response signal was as high as 15.5 times, which proves that the probe has excellent specific response capability to CN- and can effectively eliminate the interference of the above-mentioned ions and molecules.

[0077] Example 6: Practical Application of Probe in Rapid Detection of Cyanide in Wax Shots

[0078] Take one wax pellet to be tested, cut it open with a clean blade, and remove the pellet inside. Scrape approximately 1 mg of the pellet contents with a scraper and place it in a 10 mL capped centrifuge tube. Add 5 mL of methanol to the centrifuge tube and vortex for 20 s to fully dissolve the sample. Transfer 1 mL of a 10 nmol / L probe solution and add 5 μL of the sample solution. Mix well and incubate at room temperature for 3 min to allow CN- to fully interact with the recognition molecules on the probe. Use a handheld Raman spectrometer (Ocean Optics QE65 Pro, excitation wavelength 785 nm, laser power 20 mW, integration time 500 ms) to scan the spectra and acquire Raman spectra using Oceanview software. Figure 2 As shown, after adding the sample solution, the Raman shift was 2105 cm⁻¹. -1 The presence of a carbon-nitrogen triple bond at the peak indicates that the wax pellet contains CN-, while the blank control does not.

[0079] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the content and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A cyanide ratio-responsive Raman probe, characterized in that, Composed of a gold nanoparticle substrate and a cyanide ion-responsive Raman reporter molecule, the structure is shown in formula V below: Wherein, A is a gold nanomaterial substrate; X is a cyanide ion-responsive Raman reporter molecule, the structure of which is shown in Formula Ia; X is connected to the gold on the surface of A via gold-sulfur covalent bonds; A serves as the substrate for Raman signal enhancement, generating an electric field enhancement effect to amplify the Raman signal of X; X is used to achieve the quantitative determination of cyanide ions.

2. The cyanide ratio-responsive Raman probe according to claim 1, characterized in that, A is a gold nanostar with multiple tips and branches, and a particle size of 20nm-150nm.

3. The cyanide ratio-responsive Raman probe according to claim 1, characterized in that, The molar ratio of X to A is 5 × 10. 3 1~3×10 4 :

1.

4. The cyanide ratio-responsive Raman probe according to claim 1, characterized in that, The Raman spectrum of the substance shown in Formula V has one or more of the following characteristic peaks: 585 cm⁻¹ -1 717cm -1 943cm -1 1197cm -1 1301cm -1 1448cm -1 1507cm -1 1564cm -1 2105cm -1 .

5. A method for preparing a cyanide ratio-responsive Raman probe as described in any one of claims 1-4, characterized in that, Includes the following steps: S1, Preparation of cyanide ion-responsive Raman reporter molecule Ia; S2, gold nanostar substrates were prepared using the seed growth method; S3, the reporter molecule Ia obtained in step S1 is assembled with the gold nanostar substrate obtained in step S2, so that the reporter molecule Ia is linked to the surface of the gold nanostar substrate through gold-sulfur covalent bonds, and the cyanide ratio-responsive Raman probe is obtained.

6. The preparation method according to claim 5, characterized in that, Step S1, the preparation of cyanide ion-responsive Raman reporter molecule Ia, includes: S1-a: 1,1,2-trimethyl-3-ethyl-1H-benzoindole and N-ethylcarbazole-3-carbaldehyde are dissolved in an organic solvent and heated under reflux to carry out a condensation reaction. After the reaction is completed, the mixture is filtered, washed and dried to obtain intermediate I-3. S1-b: The intermediate I-3 and lipoic acid were esterified in an organic solvent in the dark in the presence of dicyclohexylcarbodiimide and dimethylaminopyridine. After the reaction was completed, the mixture was evaporated and purified by chromatography to obtain the reporter molecule Ia.

7. The preparation method according to claim 5, characterized in that, Step S2, which describes the preparation of a gold nanostar substrate using a seed growth method, includes: S2-a: Under heating and boiling conditions, reduce the first aqueous solution of gold chloride with sodium citrate solution, stir the reaction until gold seeds are generated, and obtain the gold seed solution; S2-b: Under acidic conditions and stirring, the gold seed solution, silver nitrate aqueous solution, and ascorbic acid aqueous solution are added sequentially to the second gold chloride aqueous solution to generate a gold nanostar solution.

8. The preparation method according to claim 5, characterized in that, In step S3, the reaction is carried out at room temperature with stirring, and the reaction time is 20-50 minutes.

9. The application of the cyanide ratio-responsive Raman probe according to any one of claims 1-4 in the detection of cyanide, characterized in that, The concentration of the cyanide (as CN-) is 0.1 μM to 10 μM.

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