A fluorescence temperature-sensitive control method based on photonic crystals

Abstract

The present invention belongs to the field of fluorescence regulation technology, and specifically relates to a fluorescence temperature-sensitive regulation method based on photonic crystals. Based on a photonic crystal platform, the photonic band gap of the photonic crystal is used to suppress the spontaneous emission rate of fluorescence, prolong the fluorescence lifetime, thereby increasing the time for the excited state electrons to interact with the temperature of the fluorescence application environment, so that the excited state electrons return to the ground state with a greater probability through thermal non-radiative transitions to enhance the temperature sensitivity of fluorescence. The present invention is applicable to different types of temperature-sensitive fluorescent materials, such as organic fluorescent dyes, aggregation-induced luminescence materials, bioluminescent proteins, quantum dots, and rare earth luminescent materials, etc., and has the characteristics of simple preparation method, low cost, and obvious temperature sensitivity enhancement effect, which is of great significance for expanding the application range of temperature-sensitive probes.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorescence regulation, and specifically relates to a fluorescence temperature-sensitive regulation method based on photonic crystals, in particular for enhancing the temperature sensitivity of a temperature-sensitive fluorescent probe. Background Art

[0002] Fluorescence technology has extremely wide applications in many fields such as life sciences, chemical analysis, materials science, optical microscopy, etc. For example, in the field of life sciences, fluorescence is often used for cell labeling, and thus for observing cell signal transduction, molecular interactions, etc. In the field of analytical detection, fluorescent probes can be used to analyze pollutants in the environment, water quality testing, drug analysis, etc.

[0003] Since most fluorescent probes, such as organic fluorescent dyes (such as rhodamine 6G, rhodamine B, etc.), quantum dots, rare earth luminescent materials, green fluorescent protein, etc., have temperature response characteristics, that is, their fluorescence intensity, fluorescence lifetime, fluorescence emission peak shift, etc. will change with the change of surrounding temperature, fluorescent probes have become an important tool for local temperature detection. Compared with the two temperature detection methods of fluorescence lifetime and fluorescence emission peak shift, the temperature detection technology based on fluorescence intensity has the advantages of simple operation and easy calculation, which makes it widely used. However, the temperature sensitivity of fluorescence intensity of most fluorescent probes is about 1% / K, which seriously limits its possibility of detecting small temperature changes.

[0004] Therefore, a method is needed to improve the temperature sensitivity of fluorescent probes to facilitate the detection of local small temperature changes, such as monitoring the temperature response of different regions within cells to applied drugs during drug screening. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a fluorescence temperature-sensitive regulation method based on photonic crystals, which is suitable for different types of temperature-sensitive fluorescent materials, such as organic fluorescent dyes, aggregation-induced emission materials, bioluminescent proteins, quantum dots and rare earth luminescent materials, etc., and can greatly improve the temperature response sensitivity of fluorescent probes. At the same time, thanks to the large surface area of ​​photonic crystals, the fluorescence signal intensity is also greatly enhanced.

[0006] The present invention is implemented by providing a method for temperature-sensitive fluorescence control based on photonic crystals, the method specifically comprising the following steps:

[0007] Step 1: Measure the emission peak spectrum of the target fluorescence in the fluorescence application environment;

[0008] Step 2: Extract the emission peak wavelength corresponding to the peak value according to the fluorescence emission peak spectrum;

[0009] Step 3: Prepare a photonic crystal according to the emission peak wavelength in step 2;

[0010] Step 4: measuring the photonic band gap position of the prepared photonic crystal under the same conditions as the fluorescence application environment of the target fluorescence, and finding the area where the photonic band gap matches the emission peak wavelength;

[0011] Step 5: Modify the photonic crystal with the target fluorophore;

[0012] Step 6: Conduct temperature sensitivity response test on the photonic crystal platform modified with the target fluorophore.

[0013] Further preferably, if the fluorescence application environment of the target fluorescence is liquid, the photonic crystal prepared in step 3 is a hollow sphere colloidal photonic crystal or a photonic crystal with a refractive index contrast greater than 0.5 (n1 / n2>0.5).

[0014] More preferably, the photonic crystal with a refractive index contrast greater than 0.5 is a photonic crystal made of titanium dioxide.

[0015] Further preferably, in step 4, a spectrometer is used to measure the reflection peak of the photonic crystal prepared in step 3 to determine the position of the photonic band gap.

[0016] More preferably, the above method further comprises:

[0017] Step 7: Measure the fluorescence lifetime of the target fluorophore on the photonic crystal platform.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] Provided is a method for thermosensitive fluorescence control based on photonic crystals. Based on a photonic crystal platform, the photonic band gap of the photonic crystal is used to suppress the spontaneous emission rate of fluorescence, prolong the fluorescence lifetime, thereby increasing the time for the excited state electrons to interact with the temperature of the fluorescence application environment, so that the excited state electrons return to the ground state through thermal non-radiative transitions with a greater probability, so as to enhance the temperature sensitivity of fluorescence. The present invention is applicable to different types of thermosensitive fluorescent materials, such as organic fluorescent dyes, aggregation-induced luminescence materials, bioluminescent proteins, quantum dots and rare earth luminescent materials, etc., and has the characteristics of simple preparation method, low cost, and obvious temperature sensitivity enhancement effect, which is of great significance for expanding the application range of thermosensitive probes. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The emission spectrum of the Rhodamine B fluorescent dye and the reflection peak spectrum of the hollow sphere photonic crystal in Example 1;

[0021] Figure 2This is a comparison diagram of the fluorescence temperature sensitivity measurement of the Rhodamine B fluorescent dye on a glass substrate and a hollow sphere photonic crystal in Example 1;

[0022] Figure 3 This is a comparison diagram of the fluorescence lifetime of the Rhodamine B fluorescent dye on a glass substrate and a hollow spherical photonic crystal in Example 1;

[0023] Figure 4 The emission spectrum of the quantum dot luminescent material and the reflection peak spectrum of the titanium dioxide photonic crystal in Example 2;

[0024] Figure 5 This is a comparison diagram of the fluorescence temperature sensitivity measurement of the quantum dot luminescent material in Example 2 on a glass substrate and a titanium dioxide photonic crystal;

[0025] Figure 6 This is a comparison chart of the fluorescence lifetime of the quantum dot luminescent material in Example 2 on a glass substrate and a titanium dioxide photonic crystal. DETAILED DESCRIPTION

[0026] The above scheme is further described below in conjunction with specific embodiments. It should be understood that the embodiments are used to illustrate the present invention but are not limited to the application scope of the present invention.

[0027] Example 1: Experiment on enhancing the temperature sensitivity of Rhodamine B fluorescent dye in liquid environment based on hollow spherical photonic crystals:

[0028] Step 1: Measurement of emission peak spectrum of Rhodamine B fluorescent dye: Use a spectrometer to measure the emission peak spectrum of Rhodamine B solution, such as Figure 1 As shown, curve ② in the figure is the emission peak of Rhodamine B fluorescent dye;

[0029] Step 2: extracting the emission peak wavelength corresponding to the peak value according to the fluorescence emission peak spectrum, which is 585 nm in this embodiment;

[0030] Step 3: Photonic crystal preparation: Photonic crystal samples are prepared according to the peak wavelength of the experimental fluorescent dye emission peak. In this embodiment, since the fluorescence needs to work in a liquid environment, hollow sphere photonic crystals are selected to avoid the disappearance of the photonic band gap of solid sphere photonic crystals in a liquid environment due to the refractive index matching problem, specifically self-assembled hollow sphere colloidal photonic crystals;

[0031] Step 4: Photonic crystal characterization: Measure the photonic band gap of the prepared photonic crystal. Usually, the spectrometer can be used for spectral measurement in reflection mode. In this embodiment, since the photonic crystal needs to work in a liquid environment, the photonic band gap of the prepared photonic crystal is measured in a liquid environment. Figure 1As shown in the middle curve ①, the wavelength corresponding to its reflection peak coincides with the wavelength corresponding to the emission peak of the Rhodamine B solution;

[0032] Step 5: Modify the photonic crystal with the target fluorophore using conventional surface chemical reactions;

[0033] Step 6: Fluorescence temperature sensitivity measurement: Figure 2 As shown, the glass substrate modified with rhodamine B (broken line ③) and the photonic crystal substrate (broken line ④) were placed in a variable temperature environment that had been temperature calibrated, and their fluorescence intensity values ​​under different temperature conditions were measured respectively. The measurement results were fitted to obtain the specific value of the temperature sensitivity enhancement. It should be understood that the embodiment Figure 2 The temperature range shown is used to illustrate the present invention but does not limit the application scope of the present invention.

[0034] Step 7: Fluorescence lifetime measurement: In order to verify whether the photonic band gap of the prepared photonic crystal sample can effectively suppress the spontaneous emission rate of fluorescence, a fluorescent dye is modified on the surface of the photonic crystal, and its fluorescence lifetime is measured. In this embodiment, the rhodamine B dye is uniformly modified on the glass substrate and the surface of the hollow sphere photonic crystal by covalent bonding, and placed in a liquid environment. The fluorescence lifetime is measured by time-correlated single photon counting method, such as Figure 3 As shown. The fluorescence lifetime of Rhodamine B on the photonic crystal substrate (curve ⑥) is greatly extended compared to that on the glass substrate (curve ⑤), so the spontaneous emission rate of fluorescence is effectively suppressed. It should be understood that the method of modifying the surface of the hollow sphere photonic crystal with Rhodamine B in the embodiment is used to illustrate the present invention and is not limited to the application scope of the present invention. For different fluorescent dyes and photonic crystal materials, the corresponding modification method should be selected according to the actual situation.

[0035] Example 2: Experiment on enhancing the temperature sensitivity of quantum dot luminescent materials based on titanium dioxide (high refractive index contrast, i.e., refractive index contrast greater than 0.5) photonic crystals in a liquid environment:

[0036] Step 1: Measurement of emission peak spectrum of quantum dot luminescent material: Use a spectrometer to measure the emission peak spectrum of quantum dot luminescent material, such as Figure 4 As shown, curve ⑧ in the figure is the fluorescence emission peak of quantum dots;

[0037] Step 2: extracting the emission peak wavelength corresponding to the peak value according to the fluorescence emission peak spectrum, which is 625 nm in this embodiment;

[0038] Step 3: Photonic crystal preparation: Photonic crystal samples are prepared according to the peak wavelength of the fluorescence emission peak of the experimental quantum dot luminescent material. In this embodiment, since the fluorescence needs to work in a liquid environment, in order to overcome the refractive index matching problem, a high refractive index material titanium dioxide is selected to prepare the photonic crystal, specifically a titanium dioxide photonic crystal structure;

[0039] Step 4: Photonic crystal characterization: The photonic band gap of the prepared titanium dioxide photonic crystal is measured. Usually, the spectrum measurement can be performed using the reflection mode of a spectrometer. In this embodiment, since the photonic crystal needs to work in a liquid environment, the photonic band gap of the prepared titanium dioxide photonic crystal is measured in a liquid environment. The reflection peak of the photonic crystal is as follows: Figure 4 As shown in the middle curve ⑦, the wavelength corresponding to its reflection peak coincides with the wavelength corresponding to the peak of the quantum dot fluorescence emission;

[0040] Step 5: The quantum dot luminescent material is directly spin-coated onto the titanium dioxide photonic crystal;

[0041] Step 6: Fluorescence temperature sensitivity measurement: Figure 5 As shown, a glass substrate loaded with quantum dot luminescent materials (broken line ⑨) and a titanium dioxide photonic crystal substrate (broken line ⑩) are placed in a temperature-variable environment that has been temperature-calibrated, and their fluorescence intensity values ​​under different temperature conditions are measured respectively. The measurement results are fitted to obtain the specific value of the temperature sensitivity enhancement. It should be understood that the embodiment Figure 5 The temperature range shown is used to illustrate the present invention but does not limit the application scope of the present invention.

[0042] Step 7: Fluorescence lifetime measurement: In order to verify whether the photonic band gap of the prepared titanium dioxide photonic crystal sample can effectively suppress the spontaneous emission rate of fluorescence, the quantum dot luminescent material is loaded onto the titanium dioxide photonic crystal and its fluorescence lifetime is measured. In this embodiment, the quantum dot luminescent material is uniformly loaded on the glass substrate and the surface of the titanium dioxide photonic crystal by a simple spin coating method and placed in a liquid environment. The fluorescence lifetime is measured using the time-correlated single photon counting method, such as Figure 6 As shown. On the photonic crystal substrate (curve ) compared to the fluorescence lifetime of quantum dots on glass substrate (curve ) is greatly extended, so the spontaneous emission rate of fluorescence is effectively suppressed. It should be understood that the method of loading the quantum dot luminescent material on the surface of the photonic crystal in the embodiment is used to illustrate the present invention and is not limited to the scope of application of the present invention. For different types of fluorescent materials and photonic crystal materials, corresponding modification methods should be selected according to actual conditions.

Claims

1. A fluorescence temperature-sensitive control method based on photonic crystals. It is characterized in that The method specifically comprises the following steps: Step 1: measuring the emission peak spectrum of the target fluorescence in the fluorescence application liquid environment, where the target fluorescence is one of organic fluorescent dyes, aggregation-induced emission materials, bioluminescent proteins, quantum dots and rare earth luminescent materials; Step 2: Extract the emission peak wavelength corresponding to the peak value according to the fluorescence emission peak spectrum; Step 3: preparing a hollow sphere colloidal photonic crystal or a photonic crystal with a refractive index contrast greater than 0.5 according to the emission peak wavelength in step 2; Step 4: Measure the photonic band gap position of the prepared photonic crystal under the same conditions as the fluorescent application liquid environment of the target fluorescence, and find the area where the photonic band gap matches the emission peak wavelength; Step 5: Modify the photonic crystal with the target fluorophore; Step 6: Conduct temperature sensitivity response test on the photonic crystal platform modified with the target fluorophore.

2. The method for temperature-sensitive fluorescence control based on photonic crystals according to claim 1, It is characterized in that The photonic crystal with a refractive index contrast greater than 0.5 is a photonic crystal made of titanium dioxide.

3. The method for temperature-sensitive fluorescence control based on photonic crystals according to claim 1, It is characterized in that In step 4, a spectrometer is used to measure the reflection peak of the photonic crystal prepared in step 3 to determine the position of the photonic band gap.

4. The method for temperature-sensitive fluorescence control based on photonic crystals according to claim 1, It is characterized in that Also includes: Step 7: Measure the fluorescence lifetime of the target fluorophore on the photonic crystal platform.

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