A noble metal SERS substrate for detecting specific nerve agents and a preparation method thereof
By modifying capture agent molecules with multiple functional groups on the surface of the precious metal SERS substrate, the problem of difficult to achieve high sensitivity and specific detection of organic phosphine nerve agents in the prior art is solved, and the efficiency and stability of trace detection are achieved.
Patent Information
- Application Number
- CN202411027557.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-30
- Publication Date
- 2025-03-21
- Estimated Expiration
- 2044-07-30
AI Technical Summary
The prior art is difficult to achieve high sensitivity and specific detection of organic phosphine nerve agents in complex environments, especially in rapid on-site detection.
High selective capture and detection of organic phosphine nerve agents are achieved by modifying capture agent molecules with a variety of functional groups on the surface of the noble metal SERS substrate.
It realizes efficient detection of trace organic phosphine nerve agents, with the distinctive characteristics of ultra-sensitive, high specificity and high stability, and is suitable for high specificity detection in complex environments.
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Figure CN118937303B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of surface enhanced Raman scattering, and in particular relates to a noble metal SERS substrate for detecting specificity of nerve agents and a preparation method thereof. Background Art
[0002] Sarin, tabun, soman and other organophosphorus nerve agents are a class of chemical substances that have severe toxic effects on the human nervous system. Even low concentrations and short-term exposure can cause serious harm to human health. Therefore, achieving on-site specific identification and rapid trace detection of organophosphorus nerve agents in complex environments is of great practical significance for maintaining public safety.
[0003] Existing methods for detecting organophosphine nerve agents include chromatography, mass spectrometry, etc. These spectroscopic techniques are often used for laboratory analysis, and the pre-treatment process is complex and time-consuming, and cannot be used for on-site rapid detection; portable ion mobility spectrometry, test strips and other on-site detection methods are not sensitive enough, and are very likely to produce false positives in complex environments, and have low specificity. The molecular detection technology based on the surface-enhanced Raman scattering effect (SERS) has the advantages of high sensitivity, good specificity, and real-time and rapid detection, and has played an important application value in the fields of food safety, medical diagnosis, environmental monitoring, and life sciences. The basic principle of SERS is that a certain wavelength of laser irradiates the surface of precious metal nanoparticles, causing the free electrons in the particles to oscillate under the action of light waves. When the electron frequency is consistent with the light wave frequency, surface plasmon resonance (SPR) will be generated. At this time, the local electric field on the surface of the particle is highly enhanced, thereby amplifying the Raman vibration order of the surface adsorbed molecules. The area with a high amplification effect is called the SERS "hotspot", which is usually the gap between particles. A prerequisite for efficient SERS detection is to confine the target molecules to the "hot spot" area on the surface of the noble metal substrate. However, organophosphine nerve agent molecules usually do not contain functional groups that can be firmly bonded to noble metals, so it is difficult to achieve efficient detection based on the SERS effect.
[0004] Due to the lack of effective surface capture / enrichment methods, the detection of organophosphine nerve agents based on the SERS effect has been difficult to break through until recent years. For example:
[0005] In 2016, Hakonen dripped a high-concentration Tabun solution onto the surface of a precious metal substrate to form a liquid film. As the solvent evaporated slowly, the surface film became thinner and thinner. Before it completely dried, the SERS spectrum of the poison molecule was obtained.
[0006] In 2018, Marta's team modified the carboxylic acid groups on the surface of gold nanoparticles and captured dimethyl methylphosphonate (DMMP, a sarin simulant) molecules on the surface through hydrogen bonding, achieving SERS detection at the ppm level.
[0007] Although these two methods have a certain surface confinement effect, they have obvious defects: all species in the solution will be concentrated at the same time during the thinning process of the liquid film, which is not specific, and the detection timing is difficult to grasp, and the signal reproducibility is poor; and although the chemical capture of the toxic agent molecules through hydrogen bonds improves the selectivity to a certain extent, the hydrogen bond force is weak and the capture efficiency of the molecules is low, so high-sensitivity detection (only ppm level) cannot be achieved. For this reason, the researchers further proposed a method based on "covalent bonding" to capture toxic agent molecules, which showed significant advantages: the Cai team of the Chinese Academy of Sciences used amine groups as capture functional groups to form covalent bonds with the phosphonic acid groups in methylphosphonic acid molecules (sarin simulants), and then efficiently captured them on the surface of gold nanocones, showing excellent selectivity and reproducibility. However, due to the low chemical activity of the amine group, the two need a coupling agent to chemically bond, the reaction conditions are harsh, and the reaction takes dozens of minutes, which is a long reaction time. Therefore, it still has certain limitations when used for rapid on-site detection. Summary of the invention
[0008] In order to overcome the defects in the prior art, the present invention provides a noble metal SERS substrate for detecting specific nerve agents and a preparation method thereof. The present invention selectively captures trace amounts of organophosphine nerve agent molecules in a complex environment by modifying the surface of the noble metal substrate with capture agent molecules having multiple functional groups, thereby achieving trace amount detection.
[0009] To achieve one of the above purposes, the present invention adopts the following technical solution:
[0010] A noble metal SERS substrate for detecting specific nerve agents, the substrate consists of a nanostructured noble metal sensitive layer with Raman enhancement effect and capture agent molecules, the capture agent molecules include an anchoring functional group that forms a stable bond with the nanostructured noble metal sensitive layer, an active functional group with a Raman scattering cross section, and a capture functional group that forms a chemical bond with the nerve agent.
[0011] Preferably, the nanostructured noble metal sensitive layer is gold, silver or a combination of both.
[0012] Preferably, the nanostructured noble metal sensitive layer is in the form of nanoparticles, nanostars, and a hierarchical structure array.
[0013] Preferably, the anchoring functional group includes one of a thiol group and an alkylphosphine group.
[0014] Preferably, the active functional group includes one or a combination of two or more of a benzene ring, a pyridine ring, and a pyrrole ring.
[0015] Preferably, the capture functional group includes one or a combination of two or more of an amine functional group, an oxime functional group, an alkoxy functional group, and an oxygen anion group.
[0016] Preferably, the thickness of the nanostructured noble metal sensitive layer is 10 nm-60 nm.
[0017] Preferably, the general structural formula of the capture agent molecule is:
[0018]
[0019] The value ranges of n1 and n2 are both 0-5, and n3 is 0 or 1.
[0020] To achieve the second objective, the present invention provides a method for preparing a noble metal SERS substrate for detecting specific nerve agents, comprising the following steps:
[0021] S1. Using a gas-liquid interface self-assembly method or a physical sputtering deposition method to obtain a nanostructured noble metal sensitive layer, i.e., a SERS substrate;
[0022] S3, configure the molar concentration to 10 -3 to 10 -6 The SERS substrate is immersed in a capture agent solution with a volume of 10-100 mL for 10 minutes to 24 hours, and then taken out and dried with nitrogen to obtain the desired SERS detection substrate.
[0023] Preferably, the solvent of the capture agent solution is one of methanol, ethanol or acetonitrile, and the solute of the capture agent solution is the capture agent molecule; and the temperature for immersing the SERS substrate is 25°C to 80°C.
[0024] The advantages of the present invention are:
[0025] (1) When the substrate of the present invention is used for SERS detection of nerve agents such as sarin, tabun, and soman, the capture agent molecules can be pre-modified on the surface of the noble metal substrate through anchoring functional groups. When the organophosphine nerve agent is exposed in the environment, the capture functional groups can selectively and specifically capture it through chemical bonding. Subsequently, a laser beam is used to collect the Raman spectrum of the substrate surface. The active functional groups effectively improve the sensitivity and detection limit of the SERS response, thereby achieving efficient detection of the target molecules.
[0026] (2) The present invention can selectively capture nerve agent molecules through specific chemical bonding of the capture functional group. It not only has anti-interference ability, but also has strong environmental adaptability, and is suitable for high-specificity detection in complex environments. Even if the capture functional group captures a small amount of nerve agent molecules, the presence of the active functional group in the capture agent molecule will cause the SERS spectrum to react, thereby improving the detection sensitivity and detection limit.
[0027] (3) The present invention modifies the surface of a noble metal substrate with capture agent molecules having multiple functional groups to highly selectively capture trace amounts of organophosphine nerve agent molecules in a complex environment, thereby achieving trace amount detection. When the present invention is used for SERS detection of nerve agents, it has the remarkable characteristics of ultra-sensitivity, high specificity, and high stability.
[0028] (4) The present invention analyzes the common toxic groups of sarin, tabun, soman and other toxic agent molecules, and based on their unique strong electrophilic properties, proposes the idea of using groups with strong nucleophilic properties as capture functional groups. By optimizing the design of multiple functional groups, a precious metal SERS substrate and preparation method are provided that can achieve specific and efficient detection of organophosphine nerve agents. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 It is a schematic diagram of the structure of the present invention.
[0030] Figure 2 Schematic diagram of Example 1 of the present invention, wherein Figure (a) is a schematic diagram of using a hierarchical gold ordered array as a Raman enhanced substrate, and Figure (b) is a SERS detection Raman spectrum of 10 ppb sarin simulant methylphosphonic acid molecules on a functionalized gold substrate, reaction conditions: 25°C, no coupling agent, 60s.
[0031] Figure 3 This is a schematic diagram of Example 2 of the present invention, wherein Figure (a) is a schematic diagram of using a hierarchical structured silver ordered array as a Raman enhanced substrate, and Figure (b) is a SERS detection Raman spectrum of 10 ppb sarin simulant methylphosphonic acid molecules on the functionalized silver substrate, reaction conditions: 25°C, no coupling agent, 60s. DETAILED DESCRIPTION
[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.
[0033] like Figure 1-3As shown, a noble metal SERS substrate for detecting specific nerve agents is composed of a nanostructured noble metal sensitive layer with Raman enhancement effect and capture agent molecules, and the capture agent molecules include anchoring functional groups, active functional groups and capture functional groups.
[0034] Specifically, the substrate is a solid noble metal SERS substrate, and noble metal nanoparticles are sputtered on a silicon nanocone array with a hexagonal close-packed structure using magnetron sputtering coating technology to form a noble metal film, namely a nanostructured noble metal sensitive layer, wherein the period of the array is 90nm-300nm, and the height of the silicon cone is 100nm-150nm.
[0035] Among them, the type of the nanostructured precious metal sensitive layer is gold, silver or gold-silver alloy; the thickness of the nanostructured precious metal sensitive layer is 10nm-60nm; the sputtering conditions are: sputtering current 5mA-40mA, and sputtering time 1min-15min.
[0036] The surface of the nanostructured noble metal sensitive layer is modified with capture molecules, which are composed of three groups with different functions:
[0037] ① Anchoring functional groups that form stable bonds with noble metals are one or both of thiol and alkylphosphorus, and their main function is to anchor the capture agent molecules on the surface of the noble metal sensitive layer through self-assembly;
[0038] ② Active functional groups with large Raman scattering cross sections, which are one or a combination of two or more of benzene rings, pyridine rings, and pyrrole rings. Their main function is to improve the detection sensitivity and detection limit during SERS detection.
[0039] ③ Under mild conditions, the capture functional group has a specific chemical bonding effect on nerve agents, which is one or a combination of two or more of amine functional groups, oxime functional groups, alkoxy functional groups, and oxygen anion groups. Its main function is to specifically capture the nerve agent molecules to be tested through chemical bonding.
[0040] The three groups have a certain bonding order, as shown in the schematic diagram Figure 1 shown.
[0041] A method for preparing a noble metal SERS substrate for detecting specific nerve agents comprises the following steps:
[0042] S1. Using a gas-liquid interface self-assembly method or a physical sputtering deposition method to obtain a nanostructured noble metal solid substrate, i.e., a SERS substrate;
[0043] S3, configuration concentration is 10 -3 to 10 -6The SERS substrate is immersed in a solution of 10-100 mL for 10 minutes to 24 hours, and then blown dry with nitrogen to obtain the desired SERS detection substrate.
[0044] Furthermore, based on the principle of classical oximation reaction, the capture agent molecule uses chlorocyanopyridine as a raw material, firstly thiolates it through the action of a sulfiding agent, and then undergoes amidoximation through the action of hydroxylamine hydrochloride, thereby achieving the synthesis of pyridinethioamidoamidoximate, and finally obtaining the capture agent molecule of the present invention.
[0045] The general structural formula of the capture agent molecule is:
[0046]
[0047] The value ranges of n1 and n2 are both 0-5, and n3 is 0 or 1.
[0048] Example 1
[0049] The steps of a preparation method of a noble metal SERS substrate for detecting specific nerve agents and a detection method are as follows:
[0050] (1) Using self-assembled silica microspheres as masks, a gold ordered array (size 3 mm*3 mm) with a micro-nano hierarchical structure was obtained through magnetron sputtering process as a SERS substrate, such as Figure 2 (a)
[0051] (2) NH2(CH2)3C5H3NSH containing thiol, pyridine and amine groups was selected as the capture agent molecule, and methanol was used as the solvent to prepare a concentration of 10 -6 The SERS substrate was immersed in the capture agent solution of M at room temperature (25°C) for 30 minutes, and then dried with nitrogen to obtain a noble metal SERS substrate 1. The surface signal was collected using a portable Raman spectrometer excited at a wavelength of 785 nm. The results are shown in FIG. Figure 2 As shown in the light-colored curve in (b);
[0052] (3) At room temperature, the noble metal SERS substrate 1 was immersed in 10 ppb methylphosphonic acid (a nerve agent simulant), and after 10 minutes, it was taken out and naturally dried. The surface signal was collected using a portable Raman spectrometer excited at a wavelength of 785 nm. The results are as follows: Figure 2 This is shown as the dark curve in (b).
[0053] Example 2
[0054] The steps of a preparation method of a noble metal SERS substrate for detecting specific nerve agents and a detection method are as follows:
[0055] (1) Using self-assembled polystyrene microspheres as masks, a silver micro-nano ordered array substrate (size 3 mm*3 mm) was obtained by combining reactive ion etching and physical sputtering deposition as a SERS substrate. Figure 3 (a)
[0056] (2) NOHNH2(CH2)3C5H3NSH containing thiol, pyridine, amine and oxime groups was selected as the capture agent molecule, and ethanol was used as the solvent to prepare the solution at a concentration of 10 -7 The SERS substrate was immersed in the capture agent solution of M at room temperature (25°C) for 30 minutes, and then dried with nitrogen to obtain the noble metal SERS substrate 2. The surface signal was collected using a portable Raman spectrometer excited at a wavelength of 785 nm. The results are shown in FIG. Figure 3 As shown in the light-colored curve in (b);
[0057] (3) At room temperature, the noble metal SERS substrate 2 was immersed in 10 ppb methylphosphonic acid (a nerve agent simulant), and after 10 minutes, it was taken out and naturally dried. The surface signal was collected using a portable Raman spectrometer excited at a wavelength of 785 nm. The results are as follows: Figure 3 This is shown as the dark curve in (b).
[0058] In Examples 2 and 3, amidoxime, pyridine ring and mercapto group are used as groups for capturing nerve agents, groups for indirectly "increasing" the Raman scattering cross section and groups for anchoring to the precious metal substrate, respectively. Specifically, para-mercapto-pyridine-amidoxime molecules are used as capture agent molecules.
[0059] Depend on Figure 2 (a) and Figure 3 (a) It can be seen that both Example 2 and Example 3 prepared noble metal micro-nanostructure arrays with consistent structure and rough surface as highly active SERS enhanced substrates;
[0060] like Figure 2 (b) and Figure 3 The light-colored curve at the bottom in (b) shows:
[0061] The strong vibration peak (992cm -1 ) is pyridyl, indicating that the capture agent molecule has high Raman activity; in the characteristic peak range of nerve agents (700-900cm -1 ) does not have any significant vibration peaks and therefore will not interfere with the identification of nerve agent molecules.
[0062] like Figure 2 (b) and Figure 3 The dark curve at the top in (b) shows:
[0063] Figure 2(b) At wave number 740 cm -1 The characteristic peak of the stretching vibration peak of the carbon-phosphine bond of the nerve agent is obtained at Figure 3 (b) at 760 cm -1 The characteristic carbon-phosphine bond stretching vibration peak of the nerve agent is obtained, indicating that the capture agent in the noble metal SERS substrate prepared in Example 2 and Example 3 achieves stable targeted capture of methylphosphonic acid molecules by chemical bonding.
[0064] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A noble metal SERS substrate for detecting specific nerve agents, characterized in that: The substrate is composed of a nanostructured noble metal sensitive layer with Raman enhancement effect and a capture agent molecule, wherein the capture agent molecule includes an anchoring functional group that forms a stable bond with the nanostructured noble metal sensitive layer, an active functional group with a Raman scattering cross section, and a capture functional group that forms a chemical bond with the nerve agent; the thickness of the nanostructured noble metal sensitive layer is 10nm-60nm; The general structural formula of the capture agent molecule is: ； The value ranges of n1 and n2 are both 0-5, and n3 is 0 or 1.
2. The noble metal SERS substrate for detecting specific nerve agents according to claim 1, characterized in that: The nanostructured noble metal sensitive layer is one of gold and silver or a combination of the two.
3. The noble metal SERS substrate for detecting specific nerve agents according to claim 1, characterized in that: The nanostructured noble metal sensitive layer is in the form of nanoparticles, nanostars, and a hierarchical structure array.
4. A method for preparing a noble metal SERS substrate for detecting specific nerve agents according to any one of claims 1 to 3, characterized in that: The steps include: S1. Using a gas-liquid interface self-assembly method or a physical sputtering deposition method to obtain a nanostructured noble metal sensitive layer, i.e., a SERS substrate; S3, configure the molar concentration to 10 -3 to 10 -6 The SERS substrate is immersed in a capture agent solution with a volume of 10-100 mL for 10 minutes to 24 hours, and then taken out and dried with nitrogen to obtain the desired SERS detection substrate.
5. The method for preparing a noble metal SERS substrate for detecting specific nerve agents according to claim 4, characterized in that: The solvent of the capture agent solution is one of methanol, ethanol or acetonitrile, and the solute of the capture agent solution is the capture agent molecule; the immersion temperature of the SERS substrate is 25° C. to 80° C.