CN115468944A - A single-molecule Raman fiber optical tweezers based on core-shell microlens and its manufacturing method - Google Patents

Abstract

The invention discloses monomolecular Raman fiber optical tweezers based on a core-shell microlens and a manufacturing method thereof, wherein the monomolecular Raman fiber optical tweezers comprise: the device comprises a Raman spectrometer, an optical fiber coupler, an optical fiber laser, an optical fiber probe and a core-shell micro-lens suspension liquid for containing a sample to be detected, wherein the front end of the optical fiber probe extends into the core-shell micro-lens suspension liquid. The embodiment of the invention can amplify the Raman signal of the sample by using the echo wall resonance effect of the core-shell micro lens, thereby realizing the detection of the nanoscale biological sample in the biological environment, and the invention can complete the detection without introducing exogenous substances and has high biological compatibility; based on the miniaturization of the core-shell microlens fiber probe, the single-molecule Raman spectrum can be detected in a narrow biological environment; the invention has the capability of capturing a single biomolecule, can amplify a Raman scattering signal of the biomolecule, and can be used for in-situ detection of biomacromolecules or nano-scale bacteria or viruses in a biological environment.

Description

A single-molecule Raman fiber optical tweezers based on core-shell microlens and its manufacturing method

technical field

The invention relates to the field of biomedical detection, in particular to a single-molecule Raman optical fiber optical tweezers based on a core-shell microlens and a manufacturing method thereof.

Background technique

Raman microscopy is widely used in research in the field of biomedical detection, and its bulky instruments are difficult to apply to narrow biological environments such as blood vessels, intestines, and esophagus. In order to accurately realize the accuracy of Raman spectrum detection of biomacromolecules and make the detection accuracy of Raman spectra of biomacromolecules reach the level of single molecules, there are three technical problems: First, due to the size of biomacromolecules in Therefore, the diameter of the Raman scattering spot also needs to be at the nanometer scale in order to achieve precise detection of a single biomacromolecule. Secondly, a small and flexible optical probe that can penetrate deep into the living environment is needed to realize the detection of biological macromolecules in the living environment. Finally, limited by the size of biological macromolecules, their Raman scattering signals are usually weak, making it difficult to effectively collect target Raman scattering signals in complex biological environments.

Contents of the invention

The present invention aims to solve at least one of the technical problems existing in the prior art. For this reason, the present invention proposes a single-molecule Raman optical fiber optical tweezers based on core-shell microlenses and its manufacturing method, which has a simple structure, small and flexible probes, and can amplify the Raman scattering signals of biological macromolecules at the detection position. Realize the detection of nanoscale biological samples in a biological environment.

A core-shell microlens-based single-molecule Raman optical fiber optical tweezers according to an embodiment of the first aspect of the present invention includes: a Raman spectrometer; a fiber coupler, and the Raman spectrometer is connected to the first end of the fiber coupler Fiber laser, the fiber laser is connected to the second end of the fiber coupler through an isolator; fiber probe, the third end of the fiber coupler is connected to the interface end of the fiber probe; for accommodating the The core-shell microlens suspension of the sample, the front end of the fiber probe protrudes into the core-shell microlens suspension.

A core-shell microlens-based single-molecule Raman fiber optical tweezers according to the embodiment of the first aspect of the present invention has at least the following beneficial effects:

The embodiment of the present invention utilizes the whispering gallery resonance effect of the core-shell microlens to amplify the Raman signal of the sample, thereby realizing the detection of nanoscale biological samples in a biological environment. The embodiment of the present invention can complete the detection without introducing foreign substances. It has high biocompatibility; based on the miniaturization of the core-shell microlens fiber optic probe, the detection of single-molecule Raman spectrum can be carried out in a narrow biological environment; The scattered signal is amplified, which can be used in the in-situ detection of biological macromolecules or bacteria or viruses with a size of nanometers in the biological environment.

According to some embodiments of the present invention, the fiber laser emits laser light with a wavelength of 785nm.

According to some embodiments of the present invention, the core-shell microlens suspension is a TiO2/SiO2 core-shell composite particle suspension.

According to some embodiments of the present invention, the diameter of the fiber probe is 3-5 μm, and the cone angle of the fiber probe is 60°-73°.

A method for manufacturing a single-molecule Raman optical fiber optical tweezers based on a core-shell microlens according to a second embodiment of the present invention comprises the following steps:

Obtain a fiber probe, connect the fiber probe to the third end of the fiber coupler, connect the Raman spectrometer to the first end of the fiber coupler, and connect the fiber laser to the second end of the fiber coupler through an isolator;

Preparation of core-shell microlens suspension;

Drop the core-shell microlens suspension onto the glass slide, and extend the tip of the fiber optic probe into the core-shell microlens suspension.

According to the embodiment of the second aspect of the present invention, a method for manufacturing a single-molecule Raman optical fiber optical tweezers based on core-shell microlenses has at least the following beneficial effects:

The embodiment of the present invention utilizes the whispering gallery resonance effect of the core-shell microlens to amplify the Raman signal of the sample, thereby realizing the detection of nanoscale biological samples in a biological environment. The embodiment of the present invention can complete the detection without introducing foreign substances. It has high biocompatibility; based on the miniaturization of the core-shell microlens fiber optic probe, the detection of single-molecule Raman spectrum can be carried out in a narrow biological environment; The scattered signal is amplified, which can be used in the in-situ detection of biological macromolecules or bacteria or viruses with a size of nanometers in the biological environment.

According to some embodiments of the present invention, the manufacturing method of the optical fiber probe is

Cut the optical fiber into two sections from the middle, strip off the plastic outer skin and coating layer of the middle section of the optical fiber to obtain a section of bare optical fiber, and then insert the optical fiber into the thin metal tube;

The bare fiber is melted by a carbon dioxide laser, and then the melted part is thinned to make a fiber probe.

According to some embodiments of the present invention, the specific steps for preparing the core-shell microlens suspension are as follows:

Dispersing the titanium precursor in absolute ethanol to obtain a titanium precursor solution;

SiO2 microsphere powder is added in dehydrated alcohol, obtains the ethanol dispersion liquid of SiO2 microsphere;

stirring the titanium precursor solution and adding it dropwise to the ethanol dispersion of the SiO2 microspheres, and then putting it into a constant temperature reaction vessel for reaction to obtain an ethanol dispersion of core-shell particles;

The core-shell particle ethanol dispersion was taken out and diluted with deionized water to obtain a core-shell microlens suspension.

According to some embodiments of the present invention, the reaction temperature in the reaction vessel is 28°C-42°C.

According to some embodiments of the present invention, the diameter of the SiO2 microsphere powder is 3-5 μm.

According to some embodiments of the present invention, the core-shell particles in the ethanol dispersion have a thickness of 0.05-0.1 μm.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment, wherein:

1 is a schematic diagram of the principle of a single-molecule Raman fiber optic tweezers based on core-shell microlenses in an embodiment of the present invention;

Fig. 2 is the light field intensity distribution figure in the embodiment of the present invention;

Fig. 3 is a graph of the light field intensity curve of the photon nanojet generated by the core-shell microlens in the embodiment of the present invention.

Figure number:

Raman spectrometer 100, fiber coupler 200, fiber laser 300, fiber probe 400, core-shell microlens suspension 500, core-shell microlens 510, isolator 600, fiber adjustment frame 700, glass slide 800, sample to be tested 900.

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In the description of the present invention, it should be understood that when it comes to orientation descriptions, for example, the orientation or positional relationship indicated by up, down, etc. is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description , rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus should not be construed as limiting the invention.

In the description of the present invention, a plurality refers to two or more. If the description of the first and second is only for the purpose of distinguishing the technical features, it cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features relation.

In the description of the present invention, unless otherwise clearly defined, words such as setting, installation, and connection should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

Referring to Fig. 1 , a single-molecule Raman optical fiber optical tweezers based on core-shell microlenses includes: a Raman spectrometer 100, a fiber coupler 200, a fiber laser 300, a fiber probe 400 and a core-shell microlens suspension 500 . In this embodiment, the fiber coupler 200 is a Y-shaped fiber coupler 200, the Raman spectrometer 100 is connected to the left arm of the fiber coupler 200, and the fiber laser 300 is connected to the other arm of the fiber coupler 200 left end through an isolator 600. The right end of the coupler 200 is connected to the interface end of the fiber optic probe 400, the fiber optic probe 400 is fixed on the fiber adjustment frame 700, the core-shell microlens suspension 500 containing the sample 900 to be tested is placed on the glass slide 800, and the fiber optic probe The front end of 400 protrudes into the core-shell microlens suspension 500 .

The fiber laser 300 is used to emit trapped light and excitation light. In this embodiment, the fiber laser 300 has a wavelength of 785 nm and a power of 10-60 mW. Of course, fiber lasers 300 of other wavelengths and powers can also be selected.

The core-shell microlens suspension 500 is a suspension of TiO2/SiO2 core-shell composite particles, and the core-shell microlens 510 suspension made of other microcavity materials can also be used, such as silicon compounds, titanium dioxide, crystals and polymers, etc., because Electrostatic adsorption will be generated on the surface of the optical fiber, and the core-shell microlens 510 in the core-shell microlens suspension 500 will adhere to the tip of the fiber probe 400 to obtain a core-shell microlens 510 fiber probe, which can be used under a specific wavelength of laser light. Generate a whispering gallery effect, which can amplify the Raman scattering signal of molecules. Wherein, in this embodiment, the diameter of the fiber probe 400 is 3-5 μm, and the cone angle of the fiber probe 400 is 60°-73°.

The embodiment of the present invention uses the whispering gallery resonance effect of the core-shell microlens 510 to amplify the Raman signal of the sample, thereby realizing the detection of nanoscale biological samples in a biological environment. The embodiment of the present invention can complete the detection without introducing foreign substances , with high biocompatibility; based on the miniaturization of the core-shell microlens 510 fiber optic probe, single-molecule Raman spectrum detection can be carried out in a narrow biological environment; the present invention has the ability to capture a single biomolecule, and can simultaneously The Raman scattering signal is amplified and can be used for in-situ detection of biomacromolecules or bacteria or viruses with nanoscale dimensions in a biological environment.

The present invention also relates to a method for manufacturing a single-molecule Raman optical fiber optical tweezers based on core-shell microlenses, comprising the following steps:

S100, obtain the fiber probe 400, connect the fiber probe 400 to the third end of the fiber coupler 200, connect the Raman spectrometer 100 to the first end of the fiber coupler 200, connect the fiber laser 300 to the fiber through the isolator 600 The second end of the coupler 200.

It should be noted that, in the embodiment of the present invention, the fiber probe 400 is made of a large-diameter optical fiber through the fusion tapering method. First, the optical fiber is cut into two sections from the middle, and the plastic outer skin and coating layer of the middle section of the optical fiber are stripped off. Obtain a section of bare optical fiber, and then put the optical fiber into a thin metal tube; melt the exposed optical fiber with a carbon dioxide laser, and then thin the melted part, thereby drawing the optical fiber probe 400 .

It should be noted that the specific steps of the large-core fiber through the fusion tapered method are as follows:

S101. Select the type of optical fiber. In this embodiment, the optical fiber is selected as a large-core-diameter optical fiber. The core diameter of the large-core-diameter optical fiber is 100 μm, and the type of the connector is FC/PC.

S102. Use optical fiber strippers to strip the coating layer of the middle section of the large-core-diameter optical fiber to obtain a section of exposed large-core-diameter optical fiber, and then put the large-core-diameter optical fiber in a thin metal tube to protect the large core through the thin metal tube In this embodiment, the inner diameter of the thin metal tube is 0.9-1.0 mm, the wall thickness is 0.08-0.12 mm, and the length is 10-12 cm.

S103. Place the exposed large-core-diameter fiber horizontally above the carbon dioxide laser, and let it stand for a few minutes to heat the fiber to a temperature of about 500°C to melt the large-core-diameter fiber, and then pull the melted part at a speed of 3 to 5mm/s. The required fiber probe 400 can be obtained by drawing it into an optical fiber with a diameter of 3-5 μm, a length of 10 μm, and a taper angle of 60°-73°.

S200. Prepare core-shell microlens suspension 500, taking TiO2/SiO2 core-shell composite particle suspension as an example, the specific steps are as follows:

S201. Disperse the titanium precursor in absolute ethanol to obtain a titanium precursor solution; wherein the titanium precursor is titanium alkoxide (TBT), and the concentration of the titanium precursor solution is about 0.01 mol/L.

S202, adding the SiO2 microsphere powder into absolute ethanol to obtain an ethanol dispersion of the SiO2 microsphere; wherein, the diameter of the SiO2 microsphere powder is 3-5 μm.

S203. Add the titanium precursor solution prepared in step S201 dropwise into the ethanol dispersion of SiO2 microspheres prepared in step S202 while stirring with a constant temperature stirrer, and then put it into a constant temperature reaction vessel. The reaction temperature in the reaction vessel is 28°C-42°C. In this example, react at 30°C for about 24 hours. The morphology of the prepared microlenses is characterized by transmission electron microscopy to ensure that the thickness of the core-shell structure is within the specified range, and the thickness of the TiO2 shell is controlled. At 0.05-0.1 μm, an ethanol dispersion of core-shell particles is obtained.

S204. Take out the ethanol dispersion of core-shell particles and dilute with deionized water, and then dilute with deionized water to a concentration of 4.0×104 core-shell microlenses 510 per microliter to obtain a suspension 500 of core-shell microlenses.

It should be noted that each single particle in the core-shell microlens suspension 500 can be regarded as a microlens with a core-shell structure, and the refractive indices of the core and the shell are 2-2.5 and 1.4-1.5 respectively. The effect in the present invention is to produce the whispering gallery effect as the coupling between the microcavity and the taper fiber, it should be understood that, in addition to TiO2, the material of making this type of microcavity also includes silicon compound, titanium dioxide, crystal and polymer things etc.

S300. Place the glass slide 800 on the stage, drop the core-shell microlens suspension 500 onto the glass slide, insert the front end of the fiber probe 400 into the core-shell microlens 510 solution, and obtain the core-shell microlens 510 optical fiber probe.

Through the steps of steps S100-S300, a single-molecule Raman fiber optical tweezers based on core-shell microlenses of the present invention can be obtained. The specific workflow is described below:

Turn on the fiber laser 300, pass laser light into the fiber probe 400 through the fiber coupler 200, the front end of the fiber probe 400 will generate an optical gradient force, and capture a core-shell micro-lens 510 in the core-shell micro-lens suspension 500, Due to the electrostatic adsorption force generated on the surface of the fiber, the core-shell microlens 510 will adhere to the tip of the fiber probe. Due to the principle of total reflection of light, the evanescent field and the microsphere are used to couple the light of a specific wavelength in the microcavity. Resonance occurs to form a stable standing wave, that is, the whispering gallery effect is generated. At the same time, because the focal point of the tapered optical fiber is greater than the diameter of the microlens, an optical potential well will be generated at the front end of the core-shell microlens 510 to obtain the core-shell microlens 510 optical fiber probe. Other microlenses such as biological microlenses can also produce a whispering gallery effect under a specific wavelength of laser light on the premise that the shape, size, and refractive index meet the requirements.

When performing Raman spectrum detection, the prepared sample 900 to be tested is placed on the slide glass 800, the prepared core-shell microlens 510 fiber optic probe is inserted into the sample 900 to be tested, and the fiber laser 300 is turned on to emit at a wavelength of 785nm laser, the laser passes through the isolator 600, the fiber coupler 200, the fiber probe 400 and the core-shell microlens 510 to reach the captured sample 900 to be tested, and excites the Raman scattering signal of the sample 900 to be tested, as shown in Fig. 2, it can be seen that after the 796nm laser passes through the tapered optical fiber of this shape and the core-shell micro-lens 510 with a diameter of 3 μm, a whispering gallery effect is generated, and an optical potential well is formed at the front end of the core-shell micro-lens 510 . The Raman scattering signal is enhanced by the whispering gallery resonance effect of the core-shell microlens 510 and then transmitted to the Raman spectrometer 100 through the fiber probe 400 and the fiber coupler 200 successively.

Referring to FIG. 3 , it is a graph of the photon nanojet light field intensity curve generated by the core-shell microlens 510, and its FWHM=0.23λ, which breaks through the diffraction limit. Therefore, the core-shell microlens 510 fiber optic probe of the present application can achieve ultra-high Spatial detection resolution can be used to detect nanoscale bacteria, viruses, biological macromolecules, etc.

Wherein, the sample 900 to be tested in this embodiment may be nanoscale biological macromolecules, viruses or pathogenic bacteria, which are widely distributed in the human body and nature, and are convenient for detecting diseases and detecting the health status of humans or other animals; in Raman The Raman spectrum signal received in the spectrometer 100 can be displayed and further processed by a computer.

The manufacturing method of the single-molecule Raman optical fiber optical tweezers based on the core-shell microlens of the present invention is convenient and quick to operate, and the detection can be completed without introducing foreign substances after the preparation is completed, and has high biocompatibility; the core-shell microlens 510 optical fiber of the present invention The probe is based on the preparation of an optical fiber probe. Due to the miniaturization of the optical fiber probe, the detection of single-molecule Raman spectroscopy can be performed in a narrow biological environment; the core-shell microlens 510 optical fiber probe in the present invention has the ability to capture a single biological The ability of molecules, and the Raman scattering signal of molecules can be amplified at the same time, which can be used in the in-situ detection of biological macromolecules or bacteria or viruses with a size of nanometers in the biological environment.

The invention also relates to the application of a single-molecule Raman optical fiber optical tweezers based on the core-shell microlens, which is applied to the detection of macromolecular organisms.

The present invention combines fiber optic tweezers and core-shell microlenses 510. Fiber optic tweezers combined with core-shell microlenses 510 can generate sub-wavelength optical focal lengths, which can enhance the interaction between light and matter, and the optical potential wells generated by it can capture more stably Biomolecules at the nanometer scale, at the same time, the Raman scattering signal generated by the molecule is amplified through the whispering gallery resonance effect generated by the core-shell microlens 510, and the amplified Raman signal is transmitted to the Raman spectrometer 100 through an optical fiber, thereby realizing In situ probing of biological single molecules. The invention can be used to capture and detect biomacromolecules such as DNA and protein molecules, and at the same time solves the problem of weak Raman scattering models of such detection targets through the whispering gallery resonance effect, and has good application potential in the field of biomedicine.

The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, and within the scope of knowledge of those of ordinary skill in the art, various modifications can be made without departing from the spirit of the present invention. Variety.

Claims (10)

1. A single-molecule Raman fiber optical tweezers based on core-shell microlens, characterized in that, comprising: Raman spectrometer (100); A fiber coupler (200), the Raman spectrometer (100) is connected to the first end of the fiber coupler (200); A fiber laser (300), the fiber laser (300) is connected to the second end of the fiber coupler (200) through an isolator (600); An optical fiber probe (400), the third end of the optical fiber coupler (200) is connected to the interface end of the optical fiber probe (400); The core-shell microlens suspension (500) used to accommodate the sample to be tested (900), the front end of the fiber probe (400) protrudes into the core-shell microlens suspension (500). 2 . The single-molecule Raman fiber optic tweezers based on core-shell microlenses according to claim 1 , wherein the fiber laser ( 300 ) emits laser light with a wavelength of 785 nm. 3 . 3. a kind of single-molecule Raman optical fiber optical tweezers based on core-shell microlens according to claim 1, is characterized in that: described core-shell microlens suspension (500) is TiO2/SiO2 core-shell composite particle suspension . 4. a kind of single-molecule Raman optical fiber optical tweezers based on core-shell microlens according to claim 1, is characterized in that: the diameter of described optical fiber probe (400) is 3～5 μ m, and described optical fiber probe ( 400) with a cone angle of 60° to 73°. 5. A method for making single-molecule Raman fiber optical tweezers based on core-shell microlenses, comprising the following steps: Obtain the fiber probe (400), connect the fiber probe (400) to the third end of the fiber coupler (200), connect the Raman spectrometer (100) to the first end of the fiber coupler (200), connect the fiber The laser (300) is connected to the second end of the fiber coupler (200) through an isolator (600); preparing a core-shell microlens suspension (500); The core-shell microlens suspension (500) is dropped onto the glass slide, and the front end of the fiber optic probe (400) is inserted into the core-shell microlens suspension (500). 6. the manufacture method of a kind of single-molecule Raman optical fiber optic tweezers based on core-shell microlens according to claim 5, is characterized in that: the manufacture method of described fiber optic probe (400) is Cut the optical fiber into two sections from the middle, strip off the plastic outer skin and coating layer of the middle section of the optical fiber to obtain a section of bare optical fiber, and then insert the optical fiber into the thin metal tube; The bare optical fiber is melted by a carbon dioxide laser, and then the melted part is thinned, thereby drawing a fiber probe (400). 7. a kind of manufacture method based on the single-molecule Raman fiber optical tweezers of core-shell microlens according to claim 5, is characterized in that: the concrete step of described preparation core-shell microlens suspension (500) is Dispersing the titanium precursor in absolute ethanol to obtain a titanium precursor solution; SiO2 microsphere powder is added in dehydrated alcohol, obtains the ethanol dispersion liquid of SiO2 microsphere; stirring the titanium precursor solution and adding it dropwise to the ethanol dispersion of the SiO2 microspheres, and then putting it into a constant temperature reaction vessel for reaction to obtain an ethanol dispersion of core-shell particles; The core-shell particle ethanol dispersion is taken out and diluted with deionized water to obtain a core-shell microlens suspension (500). 8. The manufacturing method of a single-molecule Raman optical fiber optical tweezers based on core-shell microlenses according to claim 7, characterized in that: the reaction temperature in the reaction vessel is any value in 28°C-42°C . 9 . The method for manufacturing a single-molecule Raman optical fiber optical tweezers based on core-shell microlenses according to claim 7 , wherein the diameter of the SiO2 microsphere powder is 3-5 μm. 10 . The manufacturing method of single-molecule Raman optical fiber optical tweezers based on core-shell microlenses according to claim 7 , wherein the thickness of the core-shell particles in the ethanol dispersion of core-shell particles is 0.05-0.1 μm. 11 .

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