A metal nanoparticle-based plasmonic-enhanced fluorescence multilayer film optical structure, and a preparation method and applications thereof

Abstract

The present application relates to a kind of metal nanoparticle-based plasmonic enhanced fluorescence multilayer film optical structure and its preparation method and application, the multilayer film optical structure is by with self-assembly metal nanoparticle as enhancement substrate, to be measured fluorescent probe molecule is placed on the surface of the enhancement substrate and obtains.The present application is by the surface plasmon resonance of self-assembly metal nanoparticle, while effectively inhibiting fluorescent probe molecule photobleaching, greatly improves the sensitivity of fluorescence trace gas sensing, the service life of organic probe fluorescence and gas sensor reliability;Compared with the prior art glass substrate fluorescent film technology, the performance of the present application is comprehensively improved, and has good market application prospect.

Description

Technical Field

[0001] This invention belongs to the field of fluorescent gas sensing technology, and specifically relates to a multilayer optical structure based on plasmon-enhanced fluorescence using metal nanoparticles, its preparation method, and its application. Background Technology

[0002] Fluorescence technology, as a photoluminescence optical phenomenon, has shown great application potential in various fields such as optoelectronic devices, biomedical imaging, and fluorescence detection. However, a considerable number of fluorescent probe materials suffer from low luminescence efficiency and severe photobleaching, thus limiting their practical application in these fields. To address this challenge, researchers have begun exploring fluorescence enhancement techniques using metal nanostructures.

[0003] Fluorescence enhancement technology using metal nanostructures 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 resonance-based fluorescence enhancement techniques in gas sensing has not received much attention or reporting. Therefore, fabricating uniform multilayer optical structures that enhance 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, its preparation method and application. The multilayer film optical structure enhances fluorescence intensity on a uniform substrate surface while effectively suppressing photobleaching of fluorescent probe molecules, which greatly improves the sensitivity, lifespan of organic probes, fluorescence and reliability of gas sensors in fluorescent trace gas sensing.

[0005] This invention provides a multilayer optical structure for plasmon-enhanced fluorescence based on metal nanoparticles. The multilayer optical structure is obtained by placing the fluorescent probe molecule to be tested on the surface of the reinforcing substrate using self-assembled metal nanoparticles as the reinforcing 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 with a diameter preferably of 100 nm.

[0008] Preferably, the self-assembled metal nanoparticles are coated with a silica shell. More preferably, the silica shell is 10-20 nm thick, the purpose of which is to isolate the fluorescent molecules from the metal nanoparticles and prevent direct contact between the two from causing fluorescence quenching.

[0009] Preferably, the self-assembled metal nanoparticles are obtained by self-assembling 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 tested is a material that responds to organic compound gases; 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 analogue diphenyl chlorophosphate (DCP). Its function is to bind to the gas molecules to be tested, causing the fluorescence signal to be quenched, thereby realizing fluorescent gas sensing.

[0013] Preferably, the dispersion solution of the fluorescent probe molecules to be tested is placed on the surface of the reinforcing substrate by any one of spin coating, immersion, dip coating, drop coating, or spray coating.

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

[0015] (1) Immerse the glass slide in the prepared piranha solution, take it out, rinse it with ultrapure water, and dry it with nitrogen to obtain a hydroxylated glass slide with negative charge.

[0016] (2) Immerse the glass slide prepared in step (1) in a silane coupling agent solution, take it out, rinse it with ultrapure water, and vacuum dry it to obtain an alkylated positively charged glass slide;

[0017] (3) Take the silica-coated metal nanoparticle colloid, immerse the glass slide prepared in step (2) in the metal nanoparticle colloid, take it out, rinse it with ultrapure water and dry it with nitrogen to obtain self-assembled metal nanoparticles, which serve as an enhancement substrate.

[0018] (4) Place the fluorescent probe molecule to be tested 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] This invention also provides an application of a multilayer optical structure based on plasmon-enhanced fluorescence using metal nanoparticles in fluorescence gas correlation detection. By enhancing the fluorescence signal while suppressing photobleaching of fluorescent probe molecules, the detection limit can be lowered, detection reliability and sensitivity can be improved, and equipment requirements can be reduced.

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

[0022] Beneficial effects

[0023] This invention utilizes surface plasmon resonance of self-assembled metal nanoparticles to enhance fluorescence intensity on a uniform substrate surface while effectively suppressing photobleaching of fluorescent probe molecules. This significantly improves the sensitivity, lifespan of organic probes, fluorescence, and reliability of fluorescent trace gas sensors. Compared with existing glass substrate fluorescent thin film technology, this invention comprehensively enhances the performance of fluorescent gas sensors and has promising market application prospects. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the multilayer film optical structure of the present invention.

[0025] Figure 2 The image shows a scanning electron microscope (SEM) image of the microstructure of the self-assembled gold nanoparticle substrate prepared in Example 1.

[0026] Figure 3 ab represents the enhanced fluorescence signal on the surface of the self-assembled gold nanoparticle substrate prepared in Example 1, while suppressing the photobleaching test results.

[0027] Figure 4 This is a graph showing the quenching of fluorescent gas sensing signals over time.

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

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0030] Example 1

[0031] like Figure 1As shown, this embodiment provides a multilayer optical structure for plasmon-enhanced fluorescence based on metal nanoparticles. The multilayer optical structure is obtained by placing a fluorescent probe molecule to be tested on the surface of a self-assembled metal nanoparticle-enhanced substrate. By placing the fluorescent probe molecule to be tested on the self-assembled metal nanoparticle-enhanced substrate and then exciting the molecule with excitation light, the fluorescence signal enhancement and photobleaching suppression can be achieved by utilizing the localized surface plasmons of the metal nanoparticles to modulate the radiative attenuation rate of the fluorescent probe molecule.

[0032] The specific fabrication steps of the multilayer optical structure in this embodiment are as follows:

[0033] Step 1: Immerse the glass slide in the prepared piranha solution (H2O2 is added to H2SO4, and the volume ratio of H2O2 to H2SO4 is 1:3). After immersion for 1 hour, remove the glass slide, rinse it with ultrapure water, and dry it with nitrogen to obtain a hydroxylated glass slide with negative charge.

[0034] Step 2: Immerse 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. After immersion, remove the glass slide, rinse it with ultrapure water, and vacuum dry it to obtain an alkylated positively charged glass slide.

[0035] Step 3: Take a colloid of gold nanoparticles coated with silica with a core of 100nm, immerse the glass slide prepared in Step 2 in the colloid of gold nanoparticles, and after immersion for 12 hours, take out the glass slide after immersion, rinse it with ultrapure water and blow it dry with nitrogen to obtain self-assembled metal nanoparticles as a reinforcing 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. Place the chemical reagent bottle containing the solution into an ultrasonic machine and sonicate for 5 minutes to fully dissolve the organic probe material.

[0037] Step 5: Take 50 μL of organic probe material solution and spin-coat it at a pre-speed of 500 rpm / min for 10 s, then at a speed of 2000 rpm / min for 30 s. 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 method is not limited to gold nanoparticles; the applicable nanoparticles may be precious metals such as silver nanoparticles, copper nanoparticles, and platinum nanoparticles.

[0039] The principle of this embodiment is as follows: localized surface plasmon resonances can modulate the radiative attenuation rate of fluorescent probe molecules, increasing the radiative attenuation rate while suppressing the non-radiative attenuation rate, thereby enhancing the fluorescence signal and suppressing photobleaching. The surface enhances fluorescence while simultaneously suppressing photobleaching. The testing process is as follows: Figure 3 As shown. The organic fluorescent probe molecules at the same concentration in this embodiment were compared with a substrate without self-assembled metal nanoparticles in terms of 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 the pure glass slide substrate.

[0040] like Figure 2 The image shown is a scanning electron microscope (SEM) image of a typical microstructure 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, used to generate localized surface plasmon resonance electromagnetic waves; the metal nanoparticles are coated with a silica layer with a thickness of 10-20 nm as an isolation layer to prevent fluorescence quenching caused by direct contact between the fluorescent probe molecules and the metal; and a BK7 glass slide with a thickness of 1 mm, a length of 20 mm, and a width of 10 mm is used for electrostatic adsorption of the self-assembled substrate.

[0041] Example 2

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

[0043] This embodiment uses an organic fluorescent probe molecule capable of identifying diphenyl chlorophosphate (DCP), a sarin analogue, to detect trace amounts of DCP gas as the test sample. 50 μL of the organic fluorescent probe molecule dispersion was spin-coated onto the surfaces of a self-assembled gold nanoparticle surface-reinforced substrate and a BK7 glass substrate prepared in Example 1, and placed in a sensing gas cavity. DCP gas concentrations from high to low were sequentially injected into the sensing gas cavity through an automatic gas inlet device. The DCP gas molecules bind to the organic fluorescent probe molecules, causing fluorescence quenching of the organic fluorescent probe molecules. This fluorescence quenching gas sensing process is as follows: Figure 4 As shown, the actual detection limit for DCP gas concentration can be as low as 660 ppb. For example... Figure 5 As shown, the actual detection limit of gas concentration in this embodiment can be as low as 660 ppb, which is unattainable for fluorescent gas sensing on a pure glass slide substrate.

Claims

1. A multilayer optical structure for plasmon-enhanced fluorescence based on metal nanoparticles, characterized in that: The multilayer optical structure is obtained by placing the fluorescent probe molecule to be tested on the surface of the reinforcing substrate using self-assembled metal nanoparticles as a reinforcing substrate; the preparation method includes the following steps: (1) Immerse the glass slide in the prepared piranha solution, take it out, rinse it with ultrapure water, and blow it dry with nitrogen to obtain a hydroxylated glass slide with negative charge; (2) Immerse the glass slide prepared in step (1) in a silane coupling agent solution, take it out, rinse it with ultrapure water, and vacuum dry it to obtain an alkylated positively charged glass slide; (3) Take the silica-coated metal nanoparticle colloid, immerse the glass slide prepared in step (2) in the metal nanoparticle colloid, take it out, rinse with ultrapure water and dry with nitrogen to obtain self-assembled metal nanoparticles, which serve as an enhancement substrate. (4) Place the fluorescent probe molecule to be tested on the surface of the enhanced substrate prepared in step (3) to obtain the multilayer film optical structure.

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 silica shell.

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 self-assembly, and coordination self-assembly.

6. The multilayer film optical structure according to claim 1, characterized in that: The fluorescent probe molecule to be tested is a material that responds to organic compound gases; the response includes any one of fluorescence enhancement, fluorescence quenching, and spectral shift.

7. The multilayer film optical structure according to claim 1, characterized in that: The dispersion solution of the fluorescent probe molecules to be tested is placed on the surface of the reinforcing substrate by any one of the following methods: spin coating, immersion, dip coating, drop coating, or spray coating.

8. A method for preparing a multilayer optical structure based on metal nanoparticles and plasmon-enhanced fluorescence as described in claim 1, comprising the following steps: (1) Immerse the glass slide in the prepared piranha solution, take it out, rinse it with ultrapure water, and blow it dry with nitrogen to obtain a hydroxylated glass slide with negative charge; (2) Immerse the glass slide prepared in step (1) in a silane coupling agent solution, take it out, rinse it with ultrapure water, and vacuum dry it to obtain an alkylated positively charged glass slide; (3) Take the silica-coated metal nanoparticle colloid, immerse the glass slide prepared in step (2) in the metal nanoparticle colloid, take it out, rinse with ultrapure water and dry with nitrogen to obtain self-assembled metal nanoparticles, which serve as an enhancement substrate. (4) Place the fluorescent probe molecule to be tested on the surface of the enhanced substrate prepared in step (3) to obtain the multilayer film optical structure.

9. The application of a multilayer optical structure based on metal nanoparticles and plasmon-enhanced fluorescence as described in claim 1 in fluorescence gas correlation detection.

10. The application according to claim 9, characterized in that: The fluorescent gas-related detection includes one of the following: trace fluorescent gas detection, fluorescent imaging substrate, fluorescent spectroscopy trace detection substrate, and food safety detection.

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