Plasmon enhanced fluorescence multilayer film optical structure based on metal nanoparticles and preparation method and application thereof

Abstract

The invention relates to a multi-layer film optical structure of plasmon enhanced fluorescence based on metal nanoparticles and a preparation method and application thereof, and the multi-layer film optical structure is obtained by taking self-assembled metal nanoparticles as an enhanced substrate and placing fluorescent probe molecules to be detected on the surface of the enhanced substrate. Through surface plasma resonance of the self-assembled metal nanoparticles, the fluorescence intensity is enhanced on the surface of the uniform substrate, meanwhile, the fluorescence probe molecule photobleaching is effectively inhibited, the sensitivity in fluorescence trace gas sensing is greatly improved, the service life of the organic probe is prolonged, and the reliability of the gas sensor is greatly improved; compared with the existing glass substrate fluorescent film technology, the performance of the fluorescent gas sensor is comprehensively improved, and the fluorescent gas sensor has a good market application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorescent gas sensing, and in particular relates to a multilayer film optical structure based on metal nanoparticles plasmon-enhanced fluorescence, and a preparation method and application thereof. Background Art

[0002] Fluorescence technology, as an optical phenomenon of photoluminescence, has shown great application potential in many fields such as optoelectronic devices, biomedical imaging, and fluorescence detection. However, a considerable number of fluorescent probe materials have problems such as low luminescence efficiency and severe photobleaching, which limits their practical application in the above fields. To solve this problem, researchers began to explore metal nanostructure enhanced fluorescence technology.

[0003] Metal nanostructure enhanced fluorescence technology relies on the localized surface plasmon resonance effect of metal nanostructures, which can significantly improve the luminescence efficiency of fluorescent molecules. Although researchers have made significant progress in fluorescence enhancement, the application of surface plasmon-based fluorescence enhancement technology in gas sensing has not been taken seriously or reported. Therefore, how to manufacture a uniform multilayer optical structure that enhances fluorescence has great research significance and practical application potential. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a multilayer film optical structure based on metal nanoparticles for plasmon-enhanced fluorescence, and a preparation method and application thereof. The multilayer film optical structure can enhance the fluorescence intensity on a uniform substrate surface while effectively suppressing the photobleaching of fluorescent probe molecules, thereby greatly improving the sensitivity in fluorescent trace gas sensing, the service life fluorescence of organic probes and the reliability of gas sensors.

[0005] The present invention provides a multilayer film optical structure based on metal nanoparticles for plasmon-enhanced fluorescence. The multilayer film optical structure is obtained by using self-assembled metal nanoparticles as an enhanced substrate and placing fluorescent probe molecules to be detected on the surface of the enhanced substrate.

[0006] Preferably, the metal nanoparticles include one or more of gold nanoparticles, silver nanoparticles, copper nanoparticles, and platinum nanoparticles.

[0007] More preferably, the metal nanoparticles are gold nanoparticles, preferably with a diameter of 100 nm.

[0008] Preferably, the self-assembled metal nanoparticles are coated with a silica shell layer. More preferably, the silica shell layer has a thickness of 10-20 nm, which is used to isolate the fluorescent molecules from the metal nanoparticles to avoid fluorescence quenching caused by direct contact between the two.

[0009] Preferably, the self-assembled metal nanoparticles are obtained by self-assembly of metal nanoparticles on a glass slide.

[0010] Preferably, the self-assembly method includes one or more of electrostatic self-assembly, covalent bond self-assembly, and coordination self-assembly.

[0011] Preferably, the fluorescent probe molecule to be detected is a material that responds to an organic compound gas; the response includes any one of fluorescence enhancement, fluorescence quenching, and spectral shift.

[0012] More preferably, the fluorescent probe molecule is an organic compound that can recognize the sarin drug simulant diphenyl chlorophosphate (DCP), and its function is to bind to the gas molecules to be detected, resulting in quenching of the fluorescent signal, thereby realizing fluorescent gas sensing.

[0013] Preferably, the dispersed solution of the fluorescent probe molecules to be detected is placed on the surface of the enhanced substrate by any one of spin coating, immersion, pulling, drip coating and spray coating.

[0014] The present invention also provides a method for preparing a multilayer film optical structure based on metal nanoparticles plasmon-enhanced fluorescence, comprising the following steps:

[0015] (1) Soaking a glass slide in the prepared piranha solution, taking it out, rinsing it with ultrapure water, and drying it with nitrogen to obtain a hydroxylated negatively charged glass slide;

[0016] (2) immersing the glass slide prepared in step (1) into a silane coupling agent solution, taking out, rinsing with ultrapure water, and vacuum drying to obtain an alkylated positively charged glass slide;

[0017] (3) taking the silica-coated metal nanoparticle colloid, immersing the glass slide prepared in step (2) in the metal nanoparticle colloid, taking it out, rinsing it with ultrapure water, and drying it with nitrogen to obtain self-assembled metal nanoparticles as a reinforcement substrate;

[0018] (4) Placing the fluorescent probe molecules to be detected on the surface of the enhanced substrate prepared in step (3) to obtain the multilayer film optical structure.

[0019] Preferably, the silane coupling agent solution in step (2) is a 1% 3-aminopropyltriethoxysilane solution with a pH value between 3.5 and 5.5.

[0020] The present invention also provides an application of a multilayer optical structure of metal nanoparticle-based plasmon-enhanced fluorescence in fluorescent gas correlation detection. By enhancing the fluorescence signal while suppressing the photobleaching of the fluorescent probe molecule, the detection limit can be reduced, the detection reliability and sensitivity can be improved, and the equipment requirements can be reduced.

[0021] Preferably, the fluorescent gas related detection includes one of trace fluorescent gas detection, fluorescent imaging substrate, fluorescent spectrum trace detection substrate and food safety detection.

[0022] Beneficial Effects

[0023] The present invention enhances the fluorescence intensity on a uniform substrate surface through surface plasmon resonance of self-assembled metal nanoparticles while effectively suppressing the photobleaching of fluorescent probe molecules, thereby greatly improving the sensitivity in fluorescent trace gas sensing, the service life fluorescence of organic probes and the reliability of gas sensors; compared with the existing glass substrate fluorescent film technology, the present invention comprehensively improves the performance of fluorescent gas sensors and has good market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the multilayer film optical structure of the present invention.

[0025] Figure 2 This is a scanning electron microscope image of the microstructure of the self-assembled gold nanoparticle substrate prepared in Example 1.

[0026] Figure 3 ab are the test results of enhancing the fluorescence signal on the surface of the self-assembled gold nanoparticle substrate prepared in Example 1 while inhibiting photobleaching.

[0027] Figure 4 This is the quenching diagram of the fluorescent gas sensor signal over time.

[0028] Figure 5 This is a comparison of the fluorescence gas sensing quenching rates of a pure glass slide substrate and a self-assembled gold nanoparticle substrate. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0030] Example 1

[0031] like Figure 1As shown, this embodiment provides a multilayer film optical structure based on metal nanoparticles plasmon-enhanced fluorescence, wherein the multilayer film optical structure is obtained by using self-assembled metal nanoparticles as an enhanced substrate and placing the fluorescent probe molecules to be tested on the surface of the enhanced substrate. By placing the fluorescent probe molecules to be tested on the self-assembled gold nanoparticle enhanced substrate, and then exciting the fluorescent probe molecules to be tested with excitation light, the localized surface plasmons of the metal nanoparticles are used to regulate the radiation attenuation rate of the fluorescent probe molecules to achieve fluorescence signal enhancement and photobleaching suppression.

[0032] The specific preparation steps of the multilayer film optical structure of this embodiment are:

[0033] Step 1: Soak the slide in the prepared piranha solution (H 2 O 2 Join H 2 SO 4 Middle, H 2 O 2 With H 2 SO 4 After soaking for 1 hour, the soaked glass slide was taken out, rinsed with ultrapure water, and dried with nitrogen to obtain a hydroxylated negatively charged glass slide;

[0034] Step 2: Soak the glass slide prepared in step 1 in a 1% 3-aminopropyltriethoxysilane solution with a pH value between 3.5 and 5.5 for 3 hours, then take out the soaked glass slide, rinse it with ultrapure water, and vacuum dry it to obtain an alkylated positively charged glass slide;

[0035] Step 3: Take a 100 nm core of silica-coated gold nanoparticle colloid, immerse the glass slide prepared in step 2 in the gold nanoparticle colloid, and after immersion for 12 hours, take out the immersed glass slide, rinse it with ultrapure water, and blow dry it with nitrogen to obtain self-assembled metal nanoparticles as a reinforcement substrate;

[0036] Step 4: add 10 mg of organic probe material powder to 10 ml of tetrahydrofuran to obtain a 1 mg / ml organic probe material solution, and put the chemical reagent bottle containing the solution into an ultrasonic machine for 5 minutes to fully dissolve the organic probe material;

[0037] Step 5: Take 50uL of organic probe material solution and spin coat it at a pre-rotation speed of 500rpm / min for 10s, then at a rotation speed of 2000rpm / min for 30s, and place the organic probe material solution on the surface of the self-assembled metal nanoparticles obtained in step 3 to obtain a multilayer film optical structure.

[0038] In this embodiment, the metal nanoparticles are gold nanoparticles. It should be understood that the metal nanoparticles are not limited to gold nanoparticles, and the applicable nanoparticles may be silver nanoparticles, copper nanoparticles, platinum nanoparticles and other precious metals.

[0039] The principle of this embodiment is that the localized surface plasmon can adjust the radiation decay rate of the fluorescent probe molecule, increasing the radiation decay rate of the fluorescent probe molecule while suppressing the non-radiative decay rate of the fluorescent probe molecule, thereby enhancing the fluorescence signal and suppressing photobleaching. The surface enhances fluorescence and suppresses photobleaching at the same time. The test process is as follows Figure 3 As shown. The organic fluorescent probe molecules at the same concentration in this example were compared with the substrate without self-assembled metal nanoparticles for fluorescence signal and photobleaching. Figure 3 As shown in (a), under the same excitation light, the fluorescence signal intensity in this embodiment is 4.8 times that of the pure glass slide substrate. Figure 3 As shown in (b), under the same continuous excitation light irradiation, the photobleaching rate of the organic fluorescent probe molecules in this embodiment is much lower than that on a pure glass slide substrate.

[0040] like Figure 2 The figure shows a typical microscopic structure of a self-assembled gold nanoparticle substrate prepared according to this embodiment. According to this preferred embodiment, the metal nanoparticles are made of gold with a diameter of 100 nm, which is used to generate localized surface plasmon electromagnetic waves; the thickness of the silicon dioxide layer coated with the metal particles is 10-20 nm, which is used as an isolation layer to prevent the fluorescent probe molecules from directly contacting the metal and causing fluorescence quenching; the glass slide is made of a BK7 glass slide with a thickness of 1 mm, a length of 20 mm, and a width of 10 mm, which is used for the electrostatic adsorption self-assembled substrate.

[0041] Example 2

[0042] Application of a multilayer optical structure based on metal nanoparticles plasmon-enhanced fluorescence in the field of fluorescent gas sensing:

[0043] In this embodiment, an organic sensing fluorescent probe molecule that can identify diphenyl chlorophosphate (DCP), a sarin drug simulant, is used as a test sample to detect DCP trace gas. Take 50uL of the organic sensing fluorescent probe molecule dispersion and spin-coat it on the surface of the self-assembled gold nanoparticle surface enhanced substrate and the surface of the BK7 glass substrate prepared in Example 1, place it in the sensing gas cavity, and inject DCP gas with concentrations from high to low into the sensing gas cavity in sequence through an automatic air intake device. DCP gas molecules combine with organic sensing probe molecules, causing the fluorescence of the organic sensing fluorescent probe molecules to be quenched. The gas sensing process of the fluorescence quenching is as follows: Figure 4 As shown in Figure 2, the actual detection limit of DCP gas concentration can be as low as 660ppb. Figure 5As shown, the actual detection limit of the gas concentration in this embodiment can be as low as 660 ppb, which is unattainable by fluorescent gas sensing on a pure glass slide substrate.

Claims

1. A multilayer optical structure based on metal nanoparticles for plasmon-enhanced fluorescence, characterized in that: The multilayer film optical structure is obtained by using self-assembled metal nanoparticles as an enhanced substrate and placing fluorescent probe molecules to be detected on the surface of the enhanced substrate.

2. The multilayer film optical structure according to claim 1, characterized in that: The metal nanoparticles include one or more of gold nanoparticles, silver nanoparticles, copper nanoparticles, and platinum nanoparticles.

3. The multilayer film optical structure according to claim 1, characterized in that: The self-assembled metal nanoparticles are coated with a silicon dioxide shell layer.

4. The multilayer film optical structure according to claim 1, characterized in that: The self-assembled metal nanoparticles are obtained by self-assembling metal nanoparticles on a glass slide.

5. The multilayer film optical structure according to claim 1 or 4, characterized in that: The self-assembly method includes one or more of electrostatic self-assembly, covalent bond self-assembly, and coordination self-assembly.

6. The multi-layer film optical structure according to claim 1, characterized in that: The fluorescent probe molecule to be detected is a material that responds to organic compound gas; the response includes any one of fluorescence enhancement, fluorescence quenching, and spectrum shift.

7. The multilayer film optical structure according to claim 1, characterized in that: The dispersed solution of the fluorescent probe molecules to be detected is placed on the surface of the enhanced substrate by any one of spin coating, immersion, pulling, drip coating and spray coating.

8. A method for preparing a multilayer film optical structure based on plasmon-enhanced fluorescence of metal nanoparticles, comprising the following steps: (1) Soaking a glass slide in the prepared piranha solution, taking it out, rinsing it with ultrapure water, and drying it with nitrogen to obtain a hydroxylated negatively charged glass slide; (2) immersing the glass slide prepared in step (1) into a silane coupling agent solution, taking out, rinsing with ultrapure water, and vacuum drying to obtain an alkylated positively charged glass slide; (3) taking the silica-coated metal nanoparticle colloid, immersing the glass slide prepared in step (2) in the metal nanoparticle colloid, taking it out, rinsing it with ultrapure water, and drying it with nitrogen to obtain self-assembled metal nanoparticles as a reinforcement substrate; (4) Placing the fluorescent probe molecules to be detected on the surface of the enhanced substrate prepared in step (3) to obtain the multilayer film optical structure.

9. Application of the multilayer film optical structure based on metal nanoparticles plasmon enhanced fluorescence as claimed in claim 1 in fluorescence gas correlation detection.

10. The use according to claim 9, characterized in that: The fluorescent gas related detection includes one of trace fluorescent gas detection, fluorescent imaging substrate, fluorescent spectrum trace detection substrate and food safety detection.

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