Optical fiber biosensor, preparation method thereof and optical fiber sensing system

Abstract

The invention provides an optical fiber biosensor, a preparation method thereof and an optical fiber sensing system.The optical fiber biosensor comprises an optical fiber microstructure with an optical fiber sensing part and a surface plasma resonance layer, and the outer surface of the optical fiber sensing part is coated with the surface plasma resonance layer; the surface plasma resonance layer is used for exciting the optical fiber sensing part to generate surface plasma waves and combining or adsorbing a sensing target, and the surface plasma resonance layer is an AuNPs (at) MOF composite film; the AuNPs (at) MOF composite film is combined on the outer surface of the optical fiber sensing part through a chemical modification method, the optical fiber sensing part can be excited to generate surface plasma waves, and a sensing target is combined or adsorbed, so that a sensing film corresponding to a target detection object does not need to be coated during follow-up biological sensing, and the cost is reduced. And the manufacturing cost of the optical fiber biosensor based on the LSPR effect is further reduced.

Description

Technical Field

[0001] The present invention relates to the field of optical sensing technology, and in particular to an optical fiber biosensor and a preparation method thereof, and an optical fiber sensing system. Background Art

[0002] Fiber localized surface plasmon resonance (LSPR) is an optical phenomenon at the nanoscale that has the advantages of high sensitivity, label-free detection, portability, low cost, and real-time monitoring, and shows advantages in biosensing applications.

[0003] Current fiber optic biosensors based on the LSPR effect typically involve directly modifying the optical fiber sensing region with metal nanoparticles, followed by modification with biosensitive materials. This increased modification process is time-consuming and costly, and can also affect the performance of the fiber optic biosensor. Therefore, the present invention aims to provide a fiber optic biosensor with a simple modification process and high sensitivity. Summary of the Invention

[0004] The purpose of the present invention is to provide an optical fiber biosensor and its preparation method, and an optical fiber sensing system, which are used to solve the technical problem that the existing optical fiber biosensors based on the LSPR effect have high manufacturing costs due to the complex and time-consuming modification process.

[0005] To solve the above technical problems, the present invention provides an optical fiber biosensor, comprising an optical fiber microstructure having an optical fiber sensing portion and a surface plasmon resonance layer. The surface plasmon resonance layer is coated on the outer surface of the optical fiber sensing portion. The surface plasmon resonance layer excites and generates surface plasmon waves, which bind to or adsorb the sensing target. Among them, the surface plasmon resonance layer is AuNPs@MOF composite film.

[0006] Preferably, the optical fiber microstructure further comprises a base connected to the optical fiber sensing portion, the base comprising a core layer, a cladding layer and a coating layer arranged radially from the inside out, and the optical fiber sensing portion comprises a core layer and a cladding layer arranged radially from the inside out.

[0007] Preferably, the shape of the optical fiber microstructure is any one of a cone shape, a D shape and a U shape, and the optical fiber microstructure is a single-mode optical fiber or a multi-mode optical fiber.

[0008] Preferably, the sensing target includes at least one of DNA, miRNA and protein.

[0009] Preferably, the outer surface of the optical fiber sensing portion is modified with hydroxyl groups, and the surface plasmon resonance layer is combined with the hydroxyl groups of the optical fiber sensing portion via amino groups.

[0010] Preferably, the surface plasmon resonance layer provides a connection site for pDNA; the surface plasmon resonance layer is AuNPs@UIO-66-NH2 material, and the particle diameter of the surface plasmon resonance layer is 300nm~500nm.

[0011] Accordingly, the present invention also provides a method for preparing the optical fiber biosensor as described above, the method comprising: S10, providing an optical fiber microstructure, the optical fiber microstructure including an optical fiber sensing portion; S20, bonding the surface plasmon resonance layer to the outer surface of the optical fiber sensing portion by a chemical modification method; Among them, the surface plasmon resonance layer is an AuNPs@MOF composite film, and the surface plasmon resonance layer is used to excite the optical fiber sensing part to generate surface plasmon waves and bind or adsorb the sensing target.

[0012] Preferably, step S20 specifically includes: S201, uniformly mixing a metal salt, an organic ligand, and a solvent, heating the mixture, cooling the mixture to room temperature, obtaining a composite, centrifuging the composite to obtain a supernatant and a precipitate, and vacuum drying the precipitate to obtain a metal-organic framework powder; S202, mixing the metal organic framework powder with distilled water, heating the mixture, and then ultrasonically treating the mixture to obtain a UIO-66-NH2 suspension; S203, HAuCl4 and sodium citrate aqueous solution are sequentially added to the UIO-66-NH2 suspension and stirred until the color of the resulting mixed solution turns reddish purple, and then cooled to room temperature and centrifuged and dried to obtain AuNPs@UIO-66-NH2 particles; S204, mixing the AuNPs@UIO-66-NH2 particles with distilled water and then performing ultrasonic treatment to obtain an AuNPs@UIO-66-NH2 suspension; S205, soaking the optical fiber sensing portion of the optical fiber microstructure in piranha solution, and placing the optical fiber sensing portion in the AuNPs@UIO-66-NH2 suspension after drying until a surface plasmon resonance layer is formed on the outer surface of the optical fiber sensing portion.

[0013] Preferably, in step S201: the metal salt is zirconium oxychloride, the organic ligand is 2-aminoterephthalic acid, and the heating temperature is 100°C to 140°C.

[0014] Accordingly, the present invention also provides an optical fiber biosensing system, comprising a light source, a spectrometer, and the optical fiber biosensor according to any one of the above items; One end of the optical fiber biosensor is connected to the light source, and the other end of the optical fiber biosensor is connected to the spectrometer.

[0015] The present invention has the following beneficial effects: Different from the prior art, the present invention provides an optical fiber biosensor and a preparation method thereof, as well as an optical fiber sensing system. The optical fiber biosensor comprises an optical fiber microstructure having an optical fiber sensing portion and a surface plasmon resonance layer, wherein the surface plasmon resonance layer is coated on the outer surface of the optical fiber sensing portion, excites and generates surface plasmon waves, and binds or adsorbs a sensing target, wherein the surface plasmon resonance layer is an AuNPs@MOF composite thin film. The optical fiber biosensor provided by the present invention combines the surface plasmon resonance layer of the AuNPs@MOF composite thin film on the outer surface of the optical fiber sensing portion in the optical fiber microstructure through a chemical modification method. The surface plasmon resonance layer can not only excite the optical fiber sensing portion to generate surface plasmon waves, but also bind or adsorb the sensing target, thereby eliminating the need to coat a sensing film corresponding to the target detection object during subsequent biosensing, further reducing the manufacturing cost of the optical fiber biosensor based on the LSPR effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A process flow chart of a method for preparing an optical fiber biosensor provided in an embodiment of the present invention; Figure 2 Schematic diagram of the preparation process of the AuNPs@UIO-66-NH2-induced LSPR effect optical fiber biosensor provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0018] In a first aspect, the present invention provides an optical fiber biosensor comprising an optical fiber microstructure having an optical fiber sensing portion and a surface plasmon resonance layer, wherein the surface plasmon resonance layer is coated on the outer surface of the optical fiber sensing portion, and the surface plasmon resonance layer excites and generates surface plasmon waves, which bind or adsorb a sensing target; Among them, the surface plasmon resonance layer is an AuNPs@MOF (gold nanoparticles wrapped metal organic framework) composite film.

[0019] In the embodiments of the present invention, the LSPR effect refers to the phenomenon in which free electrons on the metal surface collectively oscillate under the influence of the light field when light irradiates the surface of a metal nanostructure. Fiber-localized surface plasmon resonance (LSPR) combines this LSPR phenomenon with fiber technology. In fiber-localized surface plasmon resonance (LSPR) structures, metal nanoparticles are typically modified on the surface of the optical fiber. When these metal nanoparticles are irradiated with light of a specific wavelength, the free electrons on their surfaces interact with the electromagnetic field of the incident light, producing resonant absorption and scattering phenomena.

[0020] In an embodiment of the present invention, the optical fiber microstructure also includes a base connected to the optical fiber sensing part, the base includes a core layer, a cladding and a coating layer arranged in sequence from the inside to the outside along the radial direction, and the optical fiber sensing part includes a core layer and a cladding arranged in sequence from the inside to the outside along the radial direction.

[0021] Specifically, the primary function of the coating is to protect the fiber's core and cladding from external environmental interference, such as mechanical damage and chemical corrosion. However, since the surface plasmon resonance layer is applied to the outer surface of the optical fiber sensing portion, it is used to stimulate the generation of surface plasmon waves in the optical fiber sensing portion, thereby binding or adsorbing the sensing target. The presence of the coating increases signal transmission loss and hinders effective contact between the sensing target and the optical fiber sensing portion. This is because it isolates the interaction between the surface plasmon resonance layer and the core and cladding, hindering the generation of plasma waves and the transmission of sensing signals.

[0022] Preferably, the shape of the optical fiber microstructure is any one of a cone shape, a D shape and a U shape, and the optical fiber microstructure is a single-mode optical fiber, a multi-mode optical fiber or a special optical fiber.

[0023] In an embodiment of the present invention, the sensing target includes at least one of DNA, miRNA (micro RNA) and protein; wherein the selection of MOF material can be selected according to different sensing targets.

[0024] In an embodiment of the present invention, the outer surface of the optical fiber sensing portion is modified with hydroxyl groups, and the surface plasmon resonance layer is combined with the hydroxyl groups of the optical fiber sensing portion via amino groups.

[0025] In an embodiment of the present invention, the surface plasmon resonance layer provides a connection site for pDNA (plasmid deoxyribonucleic acid); the surface plasmon resonance layer is made of AuNPs@UIO-66-NH2 material, and the particle diameter of the surface plasmon resonance layer is 300 nm to 500 nm.

[0026] Specifically, the surface plasmon resonance layer serves as a pDNA attachment site, enabling stable binding of pDNA to the fiber optic biosensor. This attachment is crucial for detecting specific targets. For example, when a target substance specifically binds to pDNA, it causes changes in the optical properties of the surface plasmon resonance layer, allowing it to be detected by the sensor. The presence of the attachment site ensures the fixation of pDNA on the sensor surface, preventing pDNA from falling off or shifting during detection, and ensuring the accuracy and reliability of the test results.

[0027] Specifically, gold nanoparticles possess excellent electrical conductivity and surface plasmon resonance properties, which enhance the interaction between light and matter, increasing the sensitivity of the sensor. When light strikes the surface of the AuNPs@UIO-66-NH2 material, it excites surface plasmon waves, making the sensor more sensitive to tiny optical changes. Furthermore, AuNPs (gold nanoparticles) have a large specific surface area, providing more binding sites and facilitating the attachment of pDNA.

[0028] Specifically, UIO-66-NH2 material is a metal organic framework (MOF) material with zirconium ions (Zr 4+ ) as the metal center and 2-aminoterephthalic acid as the organic ligand. These metal ions and organic ligands are interconnected through coordination bonds, forming a highly ordered three-dimensional network structure. The UIO-66-NH2 material not only provides more sites for AuNP attachment but also provides sites for pDNA attachment. This nanomaterial can both stimulate LSPR and serve as a bioconnector. With a particle diameter of 300-500 nm, it is suitable for biosensing and gas sensing.

[0029] In this embodiment of the present invention, UIO-66-NH2 is chemically modified to bond the outer surface of the optical fiber sensing portion, ensuring a tight bond between the surface plasmon resonance layer and the optical fiber microstructure. This bonding method not only improves the stability and reliability of the sensor but also enhances the interaction between the evanescent wave and the surface plasmon resonance layer.

[0030] In an embodiment of the present invention, the outer surface of the optical fiber sensing portion is modified with hydroxyl groups, the surface plasmon resonance layer includes amino groups, and the surface plasmon resonance layer is combined with the hydroxyl groups of the optical fiber sensing portion via the amino groups.

[0031] Accordingly, see Figure 1 The present invention also provides a method for preparing the optical fiber biosensor as described above, the method comprising: S10, providing an optical fiber microstructure, wherein the optical fiber microstructure includes an optical fiber sensing portion.

[0032] Specifically, step S10 further includes: An optical fiber microstructure is provided, which includes an optical fiber sensing portion and a base portion connected to the optical fiber sensing portion, wherein the base portion includes a core layer, a cladding layer, and a coating layer arranged in sequence from the inside to the outside along the radial direction, and the optical fiber sensing portion includes a core layer and a cladding layer arranged in sequence from the inside to the outside along the radial direction.

[0033] Preferably, the shape of the optical fiber microstructure is any one of a cone shape, a D shape and a U shape, and the optical fiber microstructure is a single-mode optical fiber or a multi-mode optical fiber.

[0034] S20, bonding the surface plasmon resonance layer to the outer surface of the optical fiber sensing portion by a chemical modification method.

[0035] Specifically, step S20 further includes: S201, uniformly mixing a metal salt, an organic ligand, and a solvent, heating the mixture, cooling the mixture to room temperature, obtaining a composite, centrifuging the composite to obtain a supernatant and a precipitate, and vacuum drying the precipitate to obtain a metal-organic framework powder; S202, mixing the metal organic framework powder with distilled water, heating the mixture, and then ultrasonically treating the mixture to obtain a UIO-66-NH2 suspension; S203, HAuCl4 and sodium citrate aqueous solution are sequentially added to the UIO-66-NH2 suspension and stirred until the color of the resulting mixed solution turns reddish purple, and then cooled to room temperature and centrifuged and dried to obtain AuNPs@UIO-66-NH2 particles; S204, mixing the AuNPs@UIO-66-NH2 particles with distilled water and then performing ultrasonic treatment to obtain an AuNPs@UIO-66-NH2 suspension; S205, soaking the optical fiber sensing portion of the optical fiber microstructure in piranha solution, and placing the optical fiber sensing portion in the AuNPs@UIO-66-NH2 suspension after drying until a surface plasmon resonance layer is formed on the outer surface of the optical fiber sensing portion.

[0036] Among them, the surface plasmon resonance layer is an AuNPs@MOF composite film, and the surface plasmon resonance layer is used to excite the optical fiber sensing part to generate surface plasmon waves and bind or adsorb the sensing target.

[0037] Preferably, in step S201: the metal salt is zirconium oxychloride, the organic ligand is 2-aminoterephthalic acid, and the heating temperature is 100°C to 140°C.

[0038] Accordingly, the present invention also provides an optical fiber biosensing system, comprising a light source, a spectrometer, and the optical fiber biosensor according to any one of the above items; One end of the optical fiber biosensor is connected to the light source, and the other end of the optical fiber biosensor is connected to the spectrometer.

[0039] Specifically, when light waves pass through the optical fiber microstructure, they generate evanescent waves. When the frequency of these waves matches that of the free electrons generated by AuNPs in the AuNPs@MOF film, localized surface plasmon resonance (LSPR) is generated, causing the free electrons to absorb energy. The total reflection of light is destroyed at the site where the AuNPs@MOF film grows, thus achieving resonant absorption. The resonant absorption wavelength changes with the external refractive index. Therefore, the external refractive index can be detected by monitoring the resonance valley. Biosensing is essentially refractive index sensing, so biosensing can be achieved.

[0040] In the preparation method of the optical fiber biosensor provided by the present invention, a one-step modification method is used to directly prepare an AuNPs@MOF composite film on the outer surface of the optical fiber sensing part. The gold nanoparticles (AuNPs) on the AuNPs@MOF composite film stimulate the LSPR effect, and then the MOF is used to sense DNA. Compared with the optical fiber biosensor prepared by the two-step modification method (first modifying a layer of AuNPs on the optical fiber sensing part to produce the LSPR effect, and then modifying the MOF on the AuNPs to sense DNA), the sensitivity is better for the following reasons: The method provided by the present invention is to first modify AuNPs on MOF. Since MOF has a 3D structure and a large specific surface area, more AuNPs will be deposited than directly modifying AuNPs on the optical fiber sensor, making it easier to stimulate the LSPR effect, which will lead to an increase in the sensitivity of the optical fiber biosensor; at the same time, the AuNPs@MOF composite film has a sensitization effect compared to single AuNPs, which further improves the sensitivity of the optical fiber biosensor.

[0041] The technical solution of this application is now described in conjunction with specific embodiments.

[0042] Example 1: Embodiment 1 of the present invention provides a U-shaped optical fiber biosensor for measuring the refractive index of an unknown solution. The U-shaped optical fiber biosensor includes an optical fiber microstructure having an optical fiber sensing portion and a surface plasmon resonance layer. The surface plasmon resonance layer is made of UIO-66-NH2 material. The surface plasmon resonance layer is bonded to the outer surface of the optical fiber sensing portion by a chemical modification method.

[0043] See also Figures 1 to 2 , Figure 2 Schematic diagram of the preparation process of the AuNPs@UIO-66-NH2-induced LSPR effect optical fiber biosensor provided in Example 1 of the present invention; specifically, the optical fiber biosensor is a U-shaped DNA optical fiber sensor, and its preparation process is as follows: Step 1: First, take a section of multimode optical fiber with a core diameter of 62.5μm and a cladding diameter of 125μm. Then, remove the coating from the middle section of the multimode optical fiber, bend the bare fiber section, and heat the bare fiber section with the outer flame of an alcohol lamp to form a U-shaped optical fiber microstructure with a U-shaped radius of 1mm to 5mm. The U-shaped section is the optical fiber sensing part. Cut the ends of the optical fiber flat for later use. Step 2, synthesizing UIO-66-NH2 powder: first, use an electronic balance to weigh 75 mg of zirconium dichloride (ZrOCl2) and 50 mg of 2-aminoterephthalic acid (BDC-NH2) and place them in a container bottle, then weigh 1.25 g of benzoic acid (BA) and place them in a container bottle; add 5 mL of DMF (N,N-dimethylformamide), sonicate for 90 minutes, and transfer the mixture into an autoclave; then place the autoclave in a heating box and heat it at 120°C for 24 hours, then cool it to room temperature to obtain a synthetic product; then, centrifuge the synthetic product at a centrifugal speed of 8000 r / min for 10 minutes, and wash and centrifuge it with DMF and methanol three times respectively to obtain a supernatant and a precipitate; finally, dry the obtained precipitate in a vacuum drying oven at 60°C for 24 hours to obtain UIO-66-NH2 powder, which is stored at room temperature for later use; Step 3: Synthesize AuNPs@UIO-66-NH2 particles: First, weigh 50 mg of UIO-66-NH2 powder and put it into a beaker, add 30 mL of distilled water, ultrasonicate for 30 min, put it into a magnetic stirrer, and heat it to boiling on a magnetic stirrer to obtain a UIO-66-NH2 suspension with a stirring speed of 700 rpm; then, weigh 0.1 g of sodium citrate and dissolve it in 100 mL of deionized water to prepare a sodium citrate aqueous solution with a mass fraction of 1%; then, add 2 mL of 1% HAuCl4 to the boiling 30 mL of UIO-66-NH2 suspension; finally, add 1% sodium citrate aqueous solution and stir at 700 rpm until the color of the mixed solution turns reddish purple. The solution is cooled to room temperature and centrifuged to dry to obtain AuNPs@UIO-66-NH2 particles, which are stored at room temperature for later use; Step 4: Prepare AuNPs@UIO-66-NH2 suspension: 5 mg of AuNPs@UIO-66-NH2 particles were added to 5 mL of distilled water and ultrasonicated for 30 min to obtain AuNPs@UIO-66-NH2 suspension; Step five, AuNPs@UIO-66-NH2 modified optical fiber: first, prepare a piranha solution with concentrated sulfuric acid and hydrogen peroxide solution in a volume ratio of 7:3, soak the bare fiber part of the U-shaped optical fiber prepared in step one in the piranha solution for at least 30 minutes to remove impurities on the optical fiber, and modify the optical fiber surface with -OH. Afterwards, the optical fiber with -OH is dried in a natural environment, and then placed in the AuNPs@UIO-66-NH2 suspension prepared in step four for 12 hours. Since UIO-66-NH2 carries an -NH2 functional group, it can combine with -OH, thereby binding AuNPs@UIO-66-NH2 particles to the optical fiber. Due to the conductivity of AuNPs, LSPR can be excited, and UIO-66-NH2 is a 3D metal organic framework with a large specific surface area, providing more AuNPs binding sites than the optical fiber surface, resulting in a stronger LSPR signal.

[0044] Furthermore, the AuNPs@UIO-66-NH2-modified U-shaped optical fiber obtained in step five was first immersed in a 1 μM pDNA (sequence number 5'-COOH-AAGCTTCGCTGAGGAACACAT-3') solution for 24 hours to allow the pDNA to be linked to the AuNPs@UIO-66-NH2 via an amide bond. Afterwards, the optical fiber was cleaned with distilled water, and one end of the modified U-shaped optical fiber was connected to a light source and the other end to a spectrometer. When the light emitted by the light source passed through the U-shaped optical fiber, the cladding mode was excited, and the transmitted light excited localized surface plasmon resonance (LSPR) at the interface between the cladding and the AuNPs particles. The spectrometer collected and demodulated the transmitted spectrum and saved the spectral data. Next, cDNA solutions (sequence number: 5'-ATGTGT TCCTCAGCGAAGCTT-3') of different concentrations were prepared, such as 1pM, 10pM, 100pM, 1nM, 10nM, 100nM, and 1uM, to obtain LSPR curves of different concentrations for DNA detection. Because UIO-66-NH2 provides connection sites for AuNPs and pDNA, a nanomaterial can be used to excite LSPR signals and enhance sensor sensitivity.

[0045] The purpose of the present invention is to provide an optical fiber biosensor based on AuNPs@MOF stimulating LSPR effect, realizing an optical fiber biosensor in which nanomaterials stimulate LSPR signals and improve sensing sensitivity.

[0046] Different from the prior art, the present invention has the following beneficial effects: 1. The present invention utilizes AuNPs@MOF composite thin film as the excitation film and sensing film of the optical fiber biosensor based on the LSPR effect, realizing an optical fiber biosensor that uses a thin film to both stimulate the LSPR effect and simultaneously bind to the sensing target, thereby improving the sensing sensitivity and reducing the detection limit.

[0047] 2. The present invention only requires modifying one nanomaterial on the optical fiber, thereby reducing the time cost of producing the optical fiber sensor and improving production efficiency.

[0048] 3. The MOF synthesized in this invention has a large specific surface area and rich functional groups, and is stable in liquid environments, making it suitable for biosensing. The large specific surface area of ​​MOF can provide more attachment sites for AuNPs, and also provide more attachment sites for biomolecules, further improving sensor performance. It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For any details not described in individual embodiments, reference may be made to the description in other embodiments.

[0049] The above embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. An optical fiber biosensor, characterized in that: The optical fiber microstructure includes an optical fiber sensing portion and a surface plasmon resonance layer, wherein the surface plasmon resonance layer is coated on the outer surface of the optical fiber sensing portion, and the surface plasmon resonance layer excites and generates surface plasmon waves, and binds or adsorbs the sensing target; Wherein, the surface plasmon resonance layer is an AuNPs@MOF composite film.

2. The optical fiber biosensor according to claim 1, wherein The optical fiber microstructure also includes a base connected to the optical fiber sensing part, the base includes a core layer, a cladding and the coating layer arranged in sequence from the inside to the outside along the radial direction, and the optical fiber sensing part includes the core layer and the cladding arranged in sequence from the inside to the outside along the radial direction.

3. The optical fiber biosensor according to claim 2, wherein: The shape of the optical fiber microstructure is any one of a cone shape, a D shape and a U shape, and the optical fiber microstructure is a single-mode optical fiber or a multi-mode optical fiber.

4. The optical fiber biosensor according to claim 1, wherein The sensing target includes at least one of DNA, miRNA and protein.

5. The optical fiber biosensor according to claim 1, wherein The outer surface of the optical fiber sensing portion is modified with hydroxyl groups, and the surface plasmon resonance layer is combined with the hydroxyl groups of the optical fiber sensing portion via amino groups.

6. The optical fiber biosensor according to claim 5, characterized in that The surface plasmon resonance layer provides a connection site for pDNA; the surface plasmon resonance layer is made of AuNPs@UIO-66-NH2 material, and the particle diameter of the surface plasmon resonance layer is 300nm~500nm.

7. A method for preparing the optical fiber biosensor according to any one of claims 1 to 6, characterized in that: The method comprises: S10, providing an optical fiber microstructure, wherein the optical fiber microstructure includes an optical fiber sensing portion; S20, bonding a surface plasmon resonance layer to the outer surface of the optical fiber sensing portion by a chemical modification method; Wherein, the surface plasmon resonance layer is an AuNPs@MOF composite film, and the surface plasmon resonance layer is used to excite the optical fiber sensing part to generate surface plasmon waves and bind or adsorb the sensing target.

8. The method for preparing the optical fiber biosensor according to claim 7, wherein: The S20 step specifically includes: S201, uniformly mixing a metal salt, an organic ligand, and a solvent, heating the mixture, cooling the mixture to room temperature, obtaining a composite, centrifuging the composite to obtain a supernatant and a precipitate, and vacuum drying the precipitate to obtain a metal-organic framework powder; S202, mixing the metal organic framework powder with distilled water, heating, and then ultrasonically treating to obtain a UIO-66-NH2 suspension; S203, sequentially adding HAuCl4 and sodium citrate aqueous solution to the UIO-66-NH2 suspension and stirring until the color of the resulting mixed solution turns reddish purple, then cooling to room temperature and centrifugally drying to obtain AuNPs@UIO-66-NH2 particles; S204, mixing the AuNPs@UIO-66-NH2 particles with distilled water and performing ultrasonic treatment to obtain an AuNPs@UIO-66-NH2 suspension; S205, soaking the optical fiber sensing portion of the optical fiber microstructure in piranha solution, and placing the optical fiber sensing portion in the AuNPs@UIO-66-NH2 suspension after drying until the surface of the optical fiber sensing portion is combined with the surface plasmon resonance layer.

9. The method for preparing the optical fiber biosensor according to claim 7, wherein: In the step S201, the metal salt is zirconium oxychloride, the organic ligand is 2-aminoterephthalic acid, and the temperature of the heating treatment is 100° C. to 140° C.

10. A fiber optic biosensing system, characterized in that: comprising a light source, a spectrometer, and the optical fiber biosensor according to any one of claims 1 to 6; Wherein, one end of the optical fiber biosensor is connected to the light source, and the other end of the optical fiber biosensor is connected to the spectrometer.

Images