Preparation and application method of AuNPs@polyimide SERS heating chip

Abstract

The application discloses a kind of AuNPs@ polyimide SERS heating chip preparation and application method, through interface self-assembly technology preparation large-scale AuNPs array film, and transfer to the polyimide film with heating system, form AuNPs@ polyimide heating film as APHC for SERS chip, in situ heat enrichment is carried out to TNT molecule by APHC, and sample can be effectively collected from mixed system by simple operation.This flexible, heatable SERS chip has great significance for efficient, sensitive and in-situ detection of target molecules in complex environmental systems.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of gas in-situ thermal enrichment detection equipment, and particularly relates to a preparation and application method of an AuNPs@polyimide SERS heating chip. BACKGROUND

[0002] Analysis and detection of explosives, pollutants, drugs, pesticides and biochemicals are urgently needed in public safety, environmental pollution and human health. The target molecules in real samples are complex mixtures, often dispersed in different stages such as solid or aqueous solution. In particular, for trace chemicals in complex environments, efficient and real-time in-situ detection of target analytes is still a difficult challenge. A typical example is the trace detection of various explosives including 2,4,6-trinitrotoluene (TNT). As one of the most important military energy sources, the large-scale use of TNT leads to its residues in soil, water environment and other ecosystems. In addition, the low saturation pressure of TNT makes it easy to migrate, contaminate clothes and food, and pose a threat to human health and the environment. Overall, it is of great significance and challenge to develop an efficient, sensitive and in-situ method for detecting explosives in complex environmental systems.

[0003] For the detection of trace explosives, there are two main challenges, one is how to efficiently collect explosive samples dispersed in soil or water, and the other is how to distinguish analytes from various interferents in harsh and variable environments. While surface-enhanced Raman (SERS) spectroscopy has ultra-high sensitivity for the detection of multiple analytes in complex systems. Kalasung designed Au / ZnO SERS sensors of different shapes, and used in-situ principal component analysis and linear discriminant analysis to clearly distinguish PETN with an accuracy of 73.47±0.64%. In addition, various SERS substrates have been designed and manufactured for the detection or collection of analytes on irregular surfaces, and the tedious extraction process has been simplified by simple adhesion. For example, Gao successfully fabricated nano-folded structures on flexible polyethylene terephthalate (PET) and PDMS, and ingeniously utilized the tiny gap between the nanopores to achieve high-sensitivity SERS detection of TNT. However, when explosives are left in soil, clothes and other complex environments, the currently reported flexible substrates still cannot perform efficient sample collection and effective analysis. SUMMARY

[0004] The AuNPs@polyimide SERS heating chip for explosive detection in a complex environment is easy to operate, does not need pretreatment, can effectively collect samples from a mixed system to achieve identification, and has positive practical and productive significance for efficient, sensitive and original detection of target molecules remaining in a complex environment.

[0005] To achieve the above technical effects, the application adopts the following technical solutions:

[0006] A preparation method of an AuNPs@polyimide SERS heating chip comprises the following steps:

[0007] (1) Boil chloroauric acid solution in ultrapure water, quickly inject sodium citrate solution and stir to obtain first-generation gold colloid, reduce the temperature of the reaction solution to 80-90 DEG C, mix and stir the first-generation gold colloid, sodium citrate solution and ultrapure water, inject chloroauric acid every 20-30 min to obtain second-generation gold colloid; repeat the above operation until fourth-generation gold colloid is obtained;

[0008] (2) Inject the fourth-generation gold colloid into a beaker, add cyclohexane to form an oil / water interface, quickly inject ethanol to form an array-arranged gold nano film at the interface, transfer the film to a polyimide heater after the cyclohexane volatilizes, then immerse the gold nanoparticle-loaded polyimide heating film APHC in 4-aminophenylthiol 4-ATP solution to obtain an AuNPs@polyimide SERS heating chip.

[0009] Further, in step (1), the volume ratio of chloroauric acid solution, ultrapure water and sodium citrate solution is 1:99:2, and the volume ratio of the first-generation gold colloid, sodium citrate solution and ultrapure water is 55:53:2.

[0010] Further, in step (2), the concentration of the 4-aminophenylthiol solution is 10 -7 M.

[0011] The application further provides an application method of the AuNPs@polyimide SERS heating chip, comprising the following steps:

[0012] (1) Stir and boil silver nitrate in ultrapure water, inject sodium citrate and continue to stir for a period of time until the solution becomes a gray-green silver colloid, then mix and incubate the silver colloid and 4-ATP to obtain 4-ATP@AgNPs as a signal amplifier;

[0013] (2) AuNPs@polyimide SERS heating chip is immersed in different concentrations of TNT solution to capture TNT, and after being washed by ethanol or ultrapure water, the AuNPs@polyimide SERS heating chip is immersed in 4-ATP@AgNPs solution to form a "sandwich" structure to amplify the SERS signal;

[0014] (3) The AuNPs@polyimide SERS heating chip in step (2) is placed on the top of a closed culture dish, a complex environmental sample loaded with TNT is placed at the bottom of the culture dish, the heating chip is heated to 50-60℃, and after condensation is closed, ethanol is added dropwise so that TNT is captured and connected by 4-ATP; then the heating chip is immersed in 4-ATP@AgNPs solution for incubation, and SERS detection is performed after washing.

[0015] Further, in step (1), the volume ratio of the silver colloid and the 4-aminobenzene thiol solution is 9:1, and the mixed incubation time is 1-1.5 hours.

[0016] Further, in step (3), the complex environmental sample is selected from any one of soil, clothes and fruits.

[0017] Compared with the prior art, the method of the present application has the following beneficial effects: the method of the present application utilizes nanoparticle interface self-assembly combined with SERS detection technology to form a gold nanoparticle array with a certain arrangement mode at the oil / water interface, the structure is uniform and stable, the gap distribution is uniform, the repeatability is good, and a Raman enhancement effect with higher sensitivity and better repeatability than general materials can be obtained. The present application utilizes controllable heating of a polyimide film to realize in-situ thermal enrichment of TNT vapor for efficient collection and SERS detection, which is easy to operate and does not require pretreatment, and can be used as a general means to easily realize efficient collection and discrimination of the detected substance in a complex system. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a transmission electron microscope image of the fourth generation AuNPs prepared and a gas particle size statistical distribution;

[0019] Figure 2 is a scanning electron microscope image of the self-assembled gold nanoparticle film of the fourth generation AuNPs prepared;

[0020] Figure 3 is Figure 2 a macroscopic optical photograph of the film;

[0021] Figure 4 is an optical photograph of the APHC prepared for detection of a soil sample containing TNT;

[0022] Figure 5 is an optical photograph of the APHC prepared for detection of a clothes sample containing TNT;

[0023] Figure 6 is the optical photo of APHC prepared for TNT detection in fruit-like samples;

[0024] Figure 7 is the SERS spectra of different environmental samples, i.e. soil, clothes, fruit, by polyimide heater in Example 1, 2, 3.

[0025] DETAILED DESCRIPTION

[0026] The following is a detailed implementation case of the present application, which is further described in conjunction with the accompanying drawings, but the scope of protection is not limited thereto.

[0027] Example 1

[0028] (1) 1 mL of HAuCl4 solution (25 mM) was added to 99 mL of ultrapure water and heated to boiling. 2 mL of sodium citrate (78 mM) was quickly injected and kept boiling for 30 minutes. The solution was recorded as the first generation. Then the reaction temperature of the solution was set to 90°C. After that, 55 mL of the first generation sample was extracted with 53 mL of ultrapure water and 2 mL of sodium citrate solution (60 mM). Then 1 mL of HAuCl4 solution (25 mM) was injected and stirred for 30 minutes. This operation was repeated twice, and the resulting solution was recorded as the second generation. The above operation was repeated using the previous generation of gold colloid as the mother liquor to prepare the next generation of gold nanoparticles.

[0029] (2) 10 mL of the fourth generation AuNPs colloid was added to a 50 mL beaker, then 2 mL of cyclohexane was added to form an oil / water interface, followed by the rapid injection of 1 mL of ethanol solution to form a closely arranged thin film array and transfer to the polyimide film. A 4-ATP solution with a concentration of 10 -7 M was prepared, and the above APHC was immersed in it for 1 h and washed 3 times.

[0030] (3) 18 mg of AgNO3 was suspended in 100 mL of ultrapure water, and stirring was continued until boiling. Then 2 mL of 1% sodium citrate solution was quickly injected into the mixture, and the boiling was continued for 90 minutes to obtain a gray-green silver colloid. 9 mL of AgNPs was mixed with 1 mL of 10 -5 M 4-ATP solution, and incubated at room temperature for 1 hour to prepare 4-ATP@AgNPs.

[0031] (4) The above 4-ATP modified APHC was placed on the top of a closed Ф90 mm x 15 mm culture dish, and a soil sample loaded with 50 mg of TNT powder was placed at the bottom, as shown in Figure 4The APHC was heated to 60 °C for 3 h, the heating was turned off and the TNT was allowed to recrystallize and concentrate on the APHC for 1 h. The APHC was dipped in the ATP@AgNPs solution for 3 h after the addition of ethanol dropwise. The SERS detection was performed after washing and the results are shown in Figure 7 The APHC was heated to 60 °C for 3 h, the heating was turned off and the TNT was allowed to recrystallize and concentrate on the APHC for 1 h. The APHC was dipped in the ATP@AgNPs solution for 3 h after the addition of ethanol dropwise. The SERS detection was performed after washing and the results are shown in

[0032] Example 2

[0033] (1) 1 mL of HAuCl4solution (25 mM) was added to 99 mL of ultrapure water and heated to boiling. 2 mL of sodium citrate (78 mM) was injected rapidly and boiling was maintained for 30 minutes. This solution was recorded as the first generation. The reaction temperature of the solution was then set to 90 °C. After that, 55 mL of the first generation sample was extracted with 53 mL of ultrapure water and 2 mL of sodium citrate solution (60 mM). Then 1 mL of HAuCl4solution (25 mM) was injected and stirred for 30 minutes. This operation was repeated twice and the resulting solution was recorded as the second generation. The above operation was repeated using the previous generation of gold colloid as the mother liquor to prepare the next generation of gold nanoparticles.

[0034] (2) 10 mL of the fourth generation AuNPs colloid was added to a 50 mL beaker, then 2 mL of cyclohexane was added to form an oil / water interface, followed by the rapid injection of 1 mL of ethanol solution to form a close-packed thin film array and transfer to a polyimide film. A 4-ATP solution with a concentration of 10"7M was prepared, and the above APHC was immersed in it for 1 h and washed 3 times.

[0035] (3) 18 mg of AgNO3was suspended in 100 mL of ultrapure water, and stirring was continued until boiling. Then 2 mL of 1% sodium citrate solution was rapidly injected into the mixture, and after 90 minutes of continuous boiling, a gray-green silver colloid was obtained. 9 mL of AgNPs was mixed with 1 mL of 10 -5 M 4-ATP solution, and incubated at room temperature for 1 hour to prepare 4-ATP@AgNPs.

[0036] (4) The above 4-ATP modified APHC was placed on the top of a closed Ф90 mm x 15 mm culture dish, and 10 mL of 10 -2 M TNT solution was applied to the clothes and placed at the bottom of the culture dish, as shown in Figure 5 The APHC was heated to 60 °C for 3 h, the heating was turned off and the TNT was allowed to recrystallize and concentrate on the APHC for 1 h. The APHC was dipped in the ATP@AgNPs solution for 3 h after the addition of ethanol dropwise. The SERS detection was performed after washing and the results are shown in Figure 7 The APHC was heated to 60 °C for 3 h, the heating was turned off and the TNT was allowed to recrystallize and concentrate on the APHC for 1 h. The APHC was dipped in the ATP@AgNPs solution for 3 h after the addition of ethanol dropwise. The SERS detection was performed after washing and the results are shown in

[0037] Example 3

[0038] (1) 1 mL of HAuCl4 solution (25 mM) was added to 99 mL of ultrapure water and heated to boiling. 2 mL of sodium citrate (78 mM) was quickly injected and kept boiling for 30 minutes. This solution was recorded as the first generation. The reaction temperature of the solution was then set to 90 °C. After that, 53 mL of ultrapure water and 2 mL of sodium citrate solution (60 mM) were used to extract 55 mL of the first generation sample. Then 1 mL of HAuCl4 solution (25 mM) was injected and stirred for 30 minutes. This operation was repeated twice, and the resulting solution was recorded as the second generation. The above operation was repeated using the previous generation of gold colloid as the mother liquor to prepare the next generation of gold nanoparticles.

[0039] (2) 10 mL of the fourth generation AuNPs colloid was added to a 50 mL beaker, then 2 mL of cyclohexane was added to form an oil / water interface, followed by the rapid injection of 1 mL of ethanol solution to form a closely arranged thin film array and transfer to the polyimide film. The concentration of the 4-ATP solution was 10 -7 M, and the above-mentioned APHC was immersed in it for 1 h and washed 3 times.

[0040] (3) 18 mg of AgNO3 was suspended in 100 mL of ultrapure water, and stirring was continued until boiling. Then 2 mL of 1% sodium citrate solution was quickly injected into the mixture, and the boiling was continued for 90 minutes to obtain a gray-green silver colloid. 9 mL of AgNPs was mixed with 1 mL of 10 -5 M 4-ATP solution, and incubated at room temperature for 1 hour to prepare 4-ATP@AgNPs.

[0041] (4) The above-mentioned 4-ATP modified APHC was placed on the top of a closed Ф90 mm x 15 mm culture dish, 10 mL of 10 -2 M TNT solution was applied to the fruit and placed at the bottom of the culture dish, as shown in Figure 6 ; the APHC was heated to 60 °C for 3 h, and the heating was turned off for 1 h to allow the TNT to recrystallize and enrich on the APHC. After adding ethanol dropwise, it was immersed in the ATP@AgNPs solution for 3 h, and after washing, SERS detection was performed, and the detection results are shown in Figure 7 .

[0042] Although the present application has been described herein with reference to the explanatory embodiments thereof, the above-described embodiments are merely preferred embodiments of the present application, and the embodiments of the present application are not limited to the above-described embodiments, and it should be understood that those skilled in the art can design many other modifications and embodiments, which will fall within the scope and spirit of the principles disclosed in the present application.

Claims

1. A method for preparing AuNPs@polyimide SERS heating chip, characterized in that, The method comprises the following steps: (1) Boil the chloroauric acid solution in ultrapure water, quickly inject the sodium citrate solution and stir to obtain the first generation of gold colloid, reduce the temperature of the reaction solution to 80-90℃, mix the first generation of gold colloid, sodium citrate solution and ultrapure water and stir, inject chloroauric acid every 20-30 min, repeat twice to obtain the second generation of gold colloid; repeat the above operation until the fourth generation of gold colloid is obtained; (2) Inject the fourth generation of gold colloid into a beaker, add cyclohexane to form an oil / water interface, quickly inject ethanol at the interface to form an array of gold nanoparticle films, and after the cyclohexane evaporates, transfer the film to a polyimide heater, then immerse the gold nanoparticle-loaded polyimide heating film APHC in a 4-aminobenzenethiol 4-ATP solution to obtain the AuNPs@polyimide SERS heating chip.

2. The method for preparing AuNPs@polyimide SERS heating chip according to claim 1, characterized in that, The volume ratio of the chloroauric acid solution, ultrapure water and sodium citrate solution in step (1) is 1:99:2, and the volume ratio of the first generation of gold colloid, sodium citrate solution and ultrapure water is 55:53:

2.

3. The method for preparing the AuNPs@polyimide SERS heating chip according to claim 1, characterized in that, The concentration of the 4-aminobenzenethiol solution in step (2) is 10 -7 M.

4. The application method of AuNPs@polyimide SERS heating chip, characterized in that, The AuNPs@polyimide SERS heating chip is prepared by the preparation method of any one of claims 1-3, comprising the following steps: (1) Stir and boil the silver nitrate in ultrapure water, inject sodium citrate and continue to stir for a period of time, then the solution turns into a gray-green silver colloid, then incubate the silver colloid and 4-ATP to obtain 4-ATP@AgNPs as a signal amplifier; (2) Use the AuNPs@polyimide SERS heating chip to immerse in different concentrations of TNT solution for TNT capture, then after flushing with ethanol or ultrapure water, immerse in 4-ATP@AgNPs solution to form a "sandwich" structure to amplify the SERS signal; (3) Place the AuNPs@polyimide SERS heating chip of step in the top of a closed culture dish, place the complex environmental sample loaded with TNT at the bottom of the culture dish, heat the heating chip to 50-60℃, close the heating and condensation, then add ethanol dropwise to make the TNT be captured and connected by 4-ATP; then immerse the heating chip in 4-ATP@AgNPs solution for incubation, and then perform SERS detection after washing. 5.The application method of the AuNPs@polyimide SERS heating chip according to claim 4, characterized in that, The volume ratio of the silver colloid and 4-aminobenzenethiol solution in step (1) is 9:1, and the incubation time is 1-1.5 hours. 6.The application method of the AuNPs@polyimide SERS heating chip according to claim 4, characterized in that, The complex environmental sample in step (3) is selected from any one of soil, clothes and fruits.

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