CN110082341A - SERS substrate preparation based on nanosphere etching and its application in explosive TNT detection - Google Patents

Abstract

The invention discloses the SERS substrate etched based on nanosphere preparation and its applications in explosive TNT detection, it is related to Surface enhanced Raman spectroscopy detection field, it solves since explosive TNT raman scattering cross section is small, it is difficult to the problem of carrying out direct trace detection, now propose following scheme, it is the following steps are included: S1, the spin coating of single layer polystyrene microsphere in PET film: first to PET film hydrophilic treated, then PS ball mother solution is centrifuged and is moved in the mixed solution containing ethyl alcohol and methanol that volume ratio is 2:1, and PS solution concentration is finally adjusted to 2.5 w/v%, surfactant TX-100 is added in final mixture with 0.5 volume %, then the PS solution that a drop volume is about 8 μ l is spin-coated on pure PET film.The present invention realizes quick, efficient, lossless decomposition, and operates without professional person, and detection operating process is simple, by the way of detecting indirectly, can achieve lower detection limit.

Description

Preparation of SERS substrate based on nanosphere etching and its application in explosive TNT detection application

technical field

The invention relates to the field of surface-enhanced Raman spectroscopy detection, in particular to the preparation of a SERS substrate based on nanosphere etching and its application in the detection of explosive TNT.

Background technique

Surface-Enhanced Raman Spectroscopy (Surface-Enhanced Raman Spectroscopy) is a highly sensitive detection tool. Fleischmann et al. roughened the surface of a smooth silver electrode in 1974, and for the first time obtained a monolayer of pyridine adsorbed on the surface of a silver electrode. High-quality Raman spectra of molecules. However, Fleishmann believed that this was due to the roughening of the electrode surface, and the increase in the real surface area of the electrode caused the increase in the amount of adsorbed pyridine molecules, but he did not realize that the rough surface enhanced the Raman spectrum signal of the adsorbed molecules. Until 1977, the two research groups of Van Duyne and Creighton independently found that the Raman signal of each pyridine molecule adsorbed on the surface of a rough silver electrode was about 10 ⁶ stronger than that of a single pyridine molecule in solution, pointing out This is a surface enhancement effect associated with rough surfaces, known as the SERS effect. The SERS detection method overcomes the contact detection of the traditional chemical detection method and realizes the detection of trace substances without damage. It has the advantages of fast detection speed, simple sample pretreatment operation, real-time on-site detection, and obvious spectral reaction information. . With the further development of science and technology, the new generation of Raman spectroscopy detection devices are diversified, portable and intelligent, and have become a powerful means of material analysis and detection, and are widely used in various industries.

Trinitrotoluene (English: Trinitrotoluene, abbreviation: TNT) is a colorless or light yellow crystal, odorless, hygroscopic, with a melting point of 354K (80.9°C). It is explosive and is one of the commonly used explosive ingredients . Trinitrotoluene is moderately toxic and can invade through the skin, respiratory tract, and digestive tract. The main hazard is chronic poisoning, and local skin irritation can cause dermatitis. TNT is also an important part of a variety of explosives. At present, the main explosive in our country is still TNT, so detecting the existence of TNT is the main direction of explosive detection. Due to the production, preparation, transportation and use of TNT, there will be a small amount of TNT in the natural environment, which will cause serious pollution to the environment, especially the pollution of soil and water resources.

Trace explosives detection technology is mainly to detect traces of explosive particles remaining in the steam emitted by explosives and traces left on people or objects that have been in contact with explosives. At present, the detection methods of trace explosives mainly include ion mobility spectrometry, chemiluminescence, gas chromatography, infrared spectroscopy, mass spectrometry and so on. Because the above-mentioned detection techniques are either not suitable for on-site detection, and require a large amount of pre-treatment preparation of test samples, which cannot realize non-destructive testing of samples; or the detection equipment is expensive and not suitable for comprehensive promotion. Raman detection technology is an ideal detection technology due to its rapid detection and non-destructive detection characteristics. Due to the small Raman scattering cross-section of TNT molecules, it is difficult to detect low-concentration spectra by direct detection, and TNT molecules cannot effectively connect with gold and silver nanoparticles, so direct detection cannot be used. Modified with a Raman substrate, so that the Raman substrate can effectively adsorb more TNT molecules, reaching the level of trace detection. Commonly used modification reagents include cysteine, polydiacetylene, p-mercaptoaniline, etc. to form complexes with TNT molecules to facilitate detection and determination.

Reactive ion etching technology is a dry etching technology with strong anisotropy and high selectivity. It uses molecular gas plasma for etching in a vacuum system, and uses ion-induced chemical reactions to achieve anisotropic etching, that is, uses ion energy to form a damaged layer that is easy to etch on the surface of the etched layer. and promote chemical reactions, while ions can also remove surface formations to expose a clean etched surface.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the problem that direct trace detection is difficult due to the small Raman scattering cross section of explosive TNT, and proposes the preparation of SERS substrate based on nanosphere etching and its application in explosive TNT detection.

In order to achieve the above object, the present invention adopts the following technical solutions:

Preparation of SERS substrate based on nanosphere etching and its application in explosive TNT detection, including the following steps:

S1, Spin-coating of single-layer polystyrene microspheres on PET film: firstly, the PET film is treated hydrophilically, and then the PS spheroid solution is centrifuged and transferred to a mixed solution containing ethanol and methanol at a volume ratio of 2:1, And finally adjusted the concentration of PS solution to 2.5w/v%, the surfactant TX-100 was added to the final mixture at 0.5vol%, and then a drop of PS solution with a volume of about 8 μl was spin-coated on the pure PET film, on Spin at 650 rpm for 15 seconds, followed by spin coating at 1000 rpm for 1 second to remove excess liquid, keep the film in a heater for a few minutes to dry the solvent, thus obtaining a PET film with a single layer of PS spheres;

S2, Reactive ion etching: place the PET film with a single layer of PS balls in the etching chamber of a reactive ion etching machine for etching, adjust the etching time to 5min, and finally obtain a periodic pattern containing nanocones on the surface of the PET film. array to obtain a periodic nanocone array film substrate;

S3, Electron beam deposition of gold nanoparticles: The obtained periodic nanocone array film substrate is plated with gold at a rate of 0.02~0.03nm/s in the electron beam deposition system, and the thickness of the finally obtained gold nanoparticles is 30nm Raman base;

S4, modification of PET film substrate: 4-aminothiophenol is dissolved in ethanol solution with a concentration of 10-5mol/L as the original solution of 4-aminothiophenol, and then the original solution of 4-aminothiophenol is taken for a certain amount Dilute the amount with ethanol as a solvent to 10-7mol/L, then completely immerse the gold-plated Raman substrate in 10-7mol/L 4-aminothiophenol solution, soak at room temperature for 10h, take it out and wash it with deionized water Rinse three times in a row to wash away the 4-aminothiophenol molecules that are not connected to the Raman substrate, each time for 10 seconds, and then let it dry at room temperature;

S5, the synthesis of silver nanoparticles: firstly add 10ml of 9mg/ml silver nitrate solution to 490ml of deionized water, boil at a speed of 550r/min at the magneton speed, then slowly add 10ml of a mass fraction of 1 % sodium citrate solution, the solution continued to boil for 1h after the solution turned taupe;

S6, the surface modification of silver nanoparticle: get the 4-aminothiophenol solution of 10-4mol/L of 100ul and add in the silver colloid of 900ul, vibrate one hour in the shaker to reach 4-aminothiophenol molecule and The effect of sufficient adsorption of silver nanoparticles, 4-aminothiophenol molecules form strongly interacting S-Ag bonds with silver nanoparticles;

S7, the connection of TNT molecules: soak the Raman substrate soaked in 10-7mol/L 4-aminothiophenol solution in different concentrations of TNT ethanol solutions for 10h, take it out and let it dry at room temperature;

S8, Raman detection.

Preferably, the Raman detection in the step S8 includes the following steps:

S81, substrate effect verification: dissolving R6G molecules in ethanol to prepare a mother solution, and then diluting with ethanol into different concentrations of the test solution, soaking the gold-plated Raman substrate in different concentrations of R6G solutions to connect the surface to the test solution The Raman spectrum obtained by Raman measurement was used to verify the Raman effect of the prepared substrate;

S82, Verification of TNT effect: Three kinds of samples were tested respectively, one is the Raman substrate soaked in 10-7mol/L 4-aminothiophenol solution for 10h, and the other is soaked in 10-7mol/L 4-aminothiophenol The Raman substrate in the solution for 10 hours was taken out and rinsed three times, then soaked in 4-aminothiophenol-modified silver colloid for 10 hours, taken out and rinsed, and dried at room temperature for testing. The third was soaked in 10-7mol/L 4-aminobenzene Take out the Raman substrate in the thiophenol solution for 10 hours, take it out and wash it 3 times, then soak it in 10-5mol/L TNT solution for 10 hours, take it out and let it dry, and finally soak it in the silver gel modified with 4-aminothiophenol for 10 hours, take it out Rinse 3 times, dry at room temperature to be tested;

S83, TNT gradient concentration: Soak the Raman substrate in 10-7mol/L 4-aminothiophenol solution for 10h, take it out and wash it, then soak it in 10-8~10-13mol/L TNT solution for 10h, take it out After drying, soak in 4-aminothiophenol-modified silver colloid for 10 hours, remove and rinse 3 times to remove free molecules, and dry at room temperature for testing;

S84, effect verification: use a Raman spectrometer to verify the effect of the substrate and TNT against the Raman spectrum of the sample.

Preferably, the hydrophilic treatment of the PET film in the step S1 includes cutting the PET film into a square of 2.0×2.0 cm, then ultrasonically cleaning the surface with ethanol and deionized water in sequence, and after fifteen minutes, taking it out and blowing it dry with nitrogen, Then put it into a plasma cleaner for cleaning for 3 minutes to make the surface of the PET film hydrophilic, and then perform plasma cleaning for 3 minutes after the PET film is dried at room temperature.

Preferably, the Raman spectrometer is a confocal Raman spectrometer LabRAM HR Evolution type confocal Raman spectrometer, the parameters of the spectrometer are set to be 633nm as the excitation light source, the laser power is 2.5~5mW, the integration time is 10s, and the number of integration times is 3 Second-rate.

Preferably, the model of the reactive ion etching machine is ME-3A.

The beneficial effects of the present invention are:

1. The present invention realizes rapid, efficient, and non-destructive detection, and does not require professional personnel to operate, and the detection operation process is simple.

2. The indirect detection method can achieve a lower detection limit.

Description of drawings

Figure 1 is a schematic diagram of the connection of TNT molecules.

Figure 2 is a SEM image of the flexible substrate.

Figure 3 is the Raman spectrum of R6G measured on a flexible substrate.

Figure 4 shows the uniformity and repeatability testing of flexible substrates.

Fig. 5 is a TNT concentration gradient Raman spectrum and its corresponding linear regression curve.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments.

Referring to Figures 1-5, the preparation of a SERS substrate based on nanosphere etching and its application in the detection of explosive TNT includes the following steps:

S1, Spin-coating of single-layer polystyrene microspheres on PET film: firstly, the PET film is treated hydrophilically, and then the PS spheroid solution is centrifuged and transferred to a mixed solution containing ethanol and methanol at a volume ratio of 2:1, And finally adjusted the concentration of PS solution to 2.5w/v%, the surfactant TX-100 was added to the final mixture at 0.5vol%, and then a drop of PS solution with a volume of about 8 μl was spin-coated on the pure PET film, on Spin at 650 rpm for 15 seconds, followed by spin coating at 1000 rpm for 1 second to remove excess liquid, keep the film in a heater for a few minutes to dry the solvent, thus obtaining a PET film with a single layer of PS spheres;

S2, Reactive ion etching: place the PET film with a single layer of PS balls in the etching chamber of a reactive ion etching machine for etching, adjust the etching time to 5min, and finally obtain a periodic pattern containing nanocones on the surface of the PET film. array to obtain a periodic nanocone array film substrate;

S3, Electron beam deposition of gold nanoparticles: The obtained periodic nanocone array film substrate is plated with gold at a rate of 0.02~0.03nm/s in the electron beam deposition system, and the thickness of the finally obtained gold nanoparticles is 30nm Raman base;

S4, modification of PET film substrate: 4-aminothiophenol is dissolved in ethanol solution with a concentration of 10-5mol/L as the original solution of 4-aminothiophenol, and then the original solution of 4-aminothiophenol is taken for a certain amount Dilute the amount with ethanol as a solvent to 10-7mol/L, then completely immerse the gold-plated Raman substrate in 10-7mol/L 4-aminothiophenol solution, soak at room temperature for 10h, take it out and wash it with deionized water Rinse three times in a row to wash away the 4-aminothiophenol molecules that are not connected to the Raman substrate, each time for 10 seconds, and then let it dry at room temperature;

S5, the synthesis of silver nanoparticles: firstly add 10ml of 9mg/ml silver nitrate solution to 490ml of deionized water, boil at a speed of 550r/min at the magneton speed, then slowly add 10ml of a mass fraction of 1 % sodium citrate solution, the solution continued to boil for 1h after the solution turned taupe;

S6, the surface modification of silver nanoparticle: get the 4-aminothiophenol solution of 10-4mol/L of 100ul and add in the silver colloid of 900ul, vibrate one hour in the shaker to reach 4-aminothiophenol molecule and The effect of sufficient adsorption of silver nanoparticles, 4-aminothiophenol molecules form strongly interacting S-Ag bonds with silver nanoparticles;

S7, the connection of TNT molecules: soak the Raman substrate soaked in 10-7mol/L 4-aminothiophenol solution in different concentrations of TNT ethanol solutions for 10h, take it out and let it dry at room temperature;

S8, Raman detection.

In this embodiment, the Raman detection in step S8 includes the following steps:

S81, substrate effect verification: dissolving R6G molecules in ethanol to prepare a mother solution, and then diluting with ethanol into different concentrations of the test solution, soaking the gold-plated Raman substrate in different concentrations of R6G solutions to connect the surface to the test solution The Raman spectrum obtained by Raman measurement was used to verify the Raman effect of the prepared substrate;

S82, Verification of TNT effect: Three kinds of samples were tested respectively, one is the Raman substrate soaked in 10-7mol/L 4-aminothiophenol solution for 10h, and the other is soaked in 10-7mol/L 4-aminothiophenol The Raman substrate in the solution for 10 hours was taken out and rinsed three times, then soaked in 4-aminothiophenol-modified silver colloid for 10 hours, taken out and rinsed, and dried at room temperature for testing. The third was soaked in 10-7mol/L 4-aminobenzene Take out the Raman substrate in the thiophenol solution for 10 hours, take it out and wash it 3 times, then soak it in 10-5mol/L TNT solution for 10 hours, take it out and let it dry, and finally soak it in the silver gel modified with 4-aminothiophenol for 10 hours, take it out Rinse 3 times, dry at room temperature to be tested;

S83, TNT gradient concentration: Soak the Raman substrate in 10-7mol/L 4-aminothiophenol solution for 10h, take it out and wash it, then soak it in 10-8~10-13mol/L TNT solution for 10h, take it out After drying, soak in 4-aminothiophenol-modified silver colloid for 10 hours, remove and rinse 3 times to remove free molecules, and dry at room temperature for testing;

S84, effect verification: use a Raman spectrometer to verify the effect of the substrate and TNT against the Raman spectrum of the sample.

In this embodiment, the hydrophilic treatment of the PET film in step S1 includes cutting the PET film into a square of 2.0×2.0 cm, and then ultrasonically cleaning the surface with ethanol and deionized water in sequence. After fifteen minutes, take it out and blow it dry with nitrogen. Then put it into a plasma cleaner for cleaning for 3 minutes to make the surface of the PET film hydrophilic, and then perform plasma cleaning for 3 minutes after the PET film is dried at room temperature.

In this embodiment, the Raman spectrometer is a confocal Raman spectrometer LabRAM HR Evolution type confocal Raman spectrometer, the parameters of the spectrometer are set to be 633nm as the excitation light source, the laser power is 2.5~5mW, the integration time is 10s, and the number of integration times is 3 Second-rate.

In this embodiment, the model of the reactive ion etching machine is ME-3A.

In the present invention, the modification principle of the Raman substrate is as follows: 4-aminothiophenol molecules and gold nanoparticles on the Raman substrate form strongly interacting S-Au bonds, and 10-7mol/L of 4-aminobenzenesulfide The Raman spectrum of the phenol-modified Raman substrate cannot measure the characteristic peak of 4-aminothiophenol, which has no influence on the subsequent detection. The connection principle of TNT molecules is: use TNT molecules and 4-aminothiophenol molecules to form a strong π-π acceptor-donor interaction, that is, the amino group of the electron-donating 4-aminothiophenol molecule acts as a ligand and is missing There is an interaction between the electronic TNT benzene rings, which is also the basis for the subsequent connection of silver nanoparticles modified with 4-aminothiophenol molecules.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inside", "Outside", "Clockwise", "Counterclockwise", etc. or The positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, Therefore, it should not be construed as limiting the invention.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited to this. The equivalent replacement or change of the inventive concept thereof shall be included within the protection scope of the present invention.

Claims (5)

1. preparation of SERS substrate based on nanosphere etching and its application in explosive TNT detection, it is characterized in that, comprising the following steps: S1, Spin-coating of single-layer polystyrene microspheres on PET film: firstly, the PET film is treated hydrophilically, and then the PS spheroid solution is centrifuged and transferred to a mixed solution containing ethanol and methanol at a volume ratio of 2:1, And finally adjusted the concentration of PS solution to 2.5w/v%, the surfactant TX-100 was added to the final mixture at 0.5vol%, and then a drop of PS solution with a volume of about 8 μl was spin-coated on the pure PET film, on Spin at 650 rpm for 15 seconds, followed by spin coating at 1000 rpm for 1 second to remove excess liquid, keep the film in a heater for a few minutes to dry the solvent, thus obtaining a PET film with a single layer of PS spheres; S2, Reactive ion etching: place the PET film with a single layer of PS balls in the etching chamber of a reactive ion etching machine for etching, adjust the etching time to 5min, and finally obtain a periodic pattern containing nanocones on the surface of the PET film. array to obtain a periodic nanocone array film substrate; S3, Electron beam deposition of gold nanoparticles: The obtained periodic nanocone array film substrate is plated with gold at a rate of 0.02~0.03nm/s in the electron beam deposition system, and the thickness of the finally obtained gold nanoparticles is 30nm Raman base; S4, modification of PET film substrate: 4-aminothiophenol is dissolved in ethanol solution with a concentration of 10-5mol/L as the original solution of 4-aminothiophenol, and then the original solution of 4-aminothiophenol is taken for a certain amount Dilute the amount with ethanol as a solvent to 10-7mol/L, then completely immerse the gold-plated Raman substrate in 10-7mol/L 4-aminothiophenol solution, soak at room temperature for 10h, take it out and wash it with deionized water Rinse three times in a row to wash away the 4-aminothiophenol molecules that are not connected to the Raman substrate, each time for 10 seconds, and then let it dry at room temperature; S5, the synthesis of silver nanoparticles: firstly add 10ml of 9mg/ml silver nitrate solution to 490ml of deionized water, boil at a speed of 550r/min at the magneton speed, then slowly add 10ml of a mass fraction of 1 % sodium citrate solution, the solution continued to boil for 1h after the solution turned taupe; S6, the surface modification of silver nanoparticle: get the 4-aminothiophenol solution of 10-4mol/L of 100ul and add in the silver colloid of 900ul, vibrate one hour in the shaker to reach 4-aminothiophenol molecule and The effect of sufficient adsorption of silver nanoparticles, 4-aminothiophenol molecules form strongly interacting S-Ag bonds with silver nanoparticles; S7, the connection of TNT molecules: soak the Raman substrate soaked in 10-7mol/L 4-aminothiophenol solution in different concentrations of TNT ethanol solutions for 10h, take it out and let it dry at room temperature; S8, Raman detection. 2. preparation of SERS substrate based on nanosphere etching according to claim 1 and its application in explosives TNT detection, it is characterized in that, in described step S8, Raman detection comprises the following steps: S81, substrate effect verification: dissolving R6G molecules in ethanol to prepare a mother solution, and then diluting with ethanol into different concentrations of the test solution, soaking the gold-plated Raman substrate in different concentrations of R6G solutions to connect the surface to the test solution The Raman spectrum obtained by Raman measurement was used to verify the Raman effect of the prepared substrate; S82, Verification of TNT effect: Three kinds of samples were tested respectively, one is the Raman substrate soaked in 10-7mol/L 4-aminothiophenol solution for 10h, and the other is soaked in 10-7mol/L 4-aminothiophenol The Raman substrate in the solution for 10 hours was taken out and rinsed three times, then soaked in 4-aminothiophenol-modified silver colloid for 10 hours, taken out and rinsed, and dried at room temperature for testing. The third was soaked in 10-7mol/L 4-aminobenzene Take out the Raman substrate in the thiophenol solution for 10 hours, take it out and wash it 3 times, then soak it in 10-5mol/L TNT solution for 10 hours, take it out and let it dry, and finally soak it in the silver gel modified with 4-aminothiophenol for 10 hours, take it out Rinse 3 times, dry at room temperature to be tested; S83, TNT gradient concentration: Soak the Raman substrate in 10-7mol/L 4-aminothiophenol solution for 10h, take it out and wash it, then soak it in 10-8~10-13mol/L TNT solution for 10h, take it out After drying, soak in 4-aminothiophenol-modified silver colloid for 10 hours, remove and rinse 3 times to remove free molecules, and dry at room temperature for testing; S84, effect verification: use a Raman spectrometer to verify the effect of the substrate and TNT against the Raman spectrum of the sample. 3. The preparation of SERS substrate based on nanosphere etching according to claim 2 and its application in the detection of explosive TNT, is characterized in that, the PET film hydrophilic treatment in the step S1 comprises cutting the PET film into 2.0 ×2.0 cm square, then ultrasonically clean the surface with ethanol and deionized water in turn, after fifteen minutes, take it out and blow it dry with nitrogen, then put it in a plasma cleaner for 3 minutes to make the surface of PET film hydrophilic, etc. The membrane was plasma cleaned for 3 min after drying at room temperature. 4. The SERS substrate preparation based on nanosphere etching according to claim 2 or 3 and its application in the detection of explosive TNT, is characterized in that, the Raman spectrometer is a confocal Raman spectrometer LabRAM HR Evolution type Confocal Raman spectrometer, the parameters of the spectrometer are set as the excitation light source is 633nm, the laser power is 2.5~5mW, the integration time is 10s, and the number of integrations is 3 times. 5. The SERS substrate preparation based on nanosphere etching according to any one of claims 1 to 3 and its application in the detection of explosive TNT, it is characterized in that the model of the reactive ion etching machine is ME- 3A.