Exosome quantitative detection method based on aptamer functionalized tilted fiber grating combined with gold nanoparticle signal amplification

Abstract

This invention provides a quantitative detection method for exosomes based on aptamer-functionalized tilted fiber optic gratings combined with gold nanoparticle signal amplification. The detection device consists of a broadband light source, a single-mode fiber, an electrically driven polarization controller, fiber optic clamp 1, a TFBG aptamer sensor, a reaction chamber, an optical three-dimensional adjustment frame, another fiber optic clamp 2, and a spectrometer. The detection principle can be summarized as follows: light emitted from the broadband light source is transmitted through the single-mode fiber to the electrically driven polarization controller, where the incident light is modulated into a P-polarization state. The P-state light is transmitted to the TFBG aptamer sensor, which is tightly suspended and fixed in the reaction chamber by the fiber optic clamp. The final output light signal is presented as a transmission spectrum on the spectrometer. During the detection process, the MUC1 aptamer layer on the surface of the TFBG aptamer sensor selectively captures exosomes produced by breast cancer cell lines. Furthermore, by combining with CD63 aptamers to aggregate gold nanoparticles, the refractive index change on the surface of the TFBG aptamer sensor is amplified, further amplifying the drift in the transmission spectrum. By comparing the relationship between different exosome solution concentrations and the amount of transmission spectrum drift, rapid and highly sensitive quantitative detection of exosomes is achieved. This invention provides a new method for the quantitative detection of exosomes that is highly sensitive, simple to operate, and rapid, and has broad application value in early diagnosis and prognosis in clinical medicine.

Description

Technical Field

[0001] This invention relates to the fields of fiber optic sensing technology, bio-coupled technology and nanoplasm technology, and to a quantitative detection method for exosomes based on aptamer-functionalized tilted fiber optic gratings combined with gold nanoparticle signal amplification. Background Technology

[0002] Exosomes are nanoscale vesicles, approximately 30-150 nm in diameter, secreted by cells and carrying proteins, nucleic acids, lipids, and other substances. They are important carriers of intercellular information transmission and play a significant role in disease development, diagnosis, and treatment. Exosomes are characterized by their small size, low abundance, high heterogeneity, and complex sample matrices. Exosome analysis focuses on separation, enrichment, characterization, identification, and content detection. Separation methods such as differential ultracentrifugation, density gradient centrifugation, ultrafiltration, size exclusion chromatography, immunoaffinity enrichment, and polymer precipitation have been developed. Transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), electrophoresis, Western blotting, and nanoflow cytometry are used to identify morphology, particle size, concentration, and biomarkers. Furthermore, proteomics, transcriptomics, and single-particle detection techniques are combined to analyze their molecular components and functions. Related technologies are continuously developing towards rapid, sensitive, high-throughput, standardized, and clinically translatable approaches.

[0003] Exosomes, as a key detection substance in liquid biopsies, are considered promising biomarkers for early cancer diagnosis and prognosis. Simple, reliable, and sensitive cancer exosome biosensors are crucial for early cancer diagnosis and prognosis. Traditional exosome detection requires two steps: separation and detection, and suffers from drawbacks such as operational complexity, high cost, and long detection time. Therefore, research on platforms that can directly achieve exosome separation and detection is increasing daily.

[0004] Fiber optic sensing technology is a modern sensing technology that uses optical fibers as the signal transmission and sensing carrier to convert physical, chemical, and biological signals into optical signals for detection. It boasts advantages such as small size, resistance to electromagnetic interference, and the ability to perform remote and in-situ detection, and is widely used in environmental monitoring, biochemical detection, and disease diagnosis. Tilted Bragg fiber gratings (TFBGs) are a special type of fiber grating device. By tilting the grating at a certain angle to the fiber axis, they can simultaneously excite the core mode and a large number of cladding modes. Their cladding modes are highly sensitive to the external refractive index. They combine the advantages of traditional fiber gratings, such as small size, resistance to electromagnetic interference, and good stability, with the ability to achieve highly sensitive biochemical sensing. This effectively solves the problem of weak response of ordinary fiber gratings to the surrounding environment, making them an important sensing structure in the fields of biological detection, chemical analysis, and environmental monitoring. Gold-plated tilted fiber Bragg gratings (TFBGs) are composite sensing structures formed by depositing gold films on the surface of ordinary TFBG fibers. Utilizing the localized surface plasmon resonance effect of gold nanofilms, the response of the cladding mode to changes in external refractive index can be significantly enhanced, greatly improving the sensor's detection sensitivity. At the same time, the gold film surface is easy to immobilize biomolecules such as antibodies and aptamers through bioconjugation technology, providing an ideal platform for the high-specificity and high-sensitivity detection of trace biological samples. It has important research and application value in the fields of biochemical sensing and precision detection. Summary of the Invention

[0005] To overcome the shortcomings of traditional detection technologies, this invention provides a quantitative detection method for exosomes based on aptamer-functionalized tilted fiber optic gratings combined with gold nanoparticle signal amplification. The method is characterized by: a detection device comprising a broadband light source, a single-mode optical fiber, an electrically driven polarization controller, an optical fiber clamp 1, a TFBG aptamer sensor, a reaction chamber, an optical three-dimensional adjustment frame, an optical fiber clamp 2, and a spectrometer; the broadband light source is connected to the input end of the electrically driven polarization controller via a single-mode optical fiber; the output end of the electrically driven polarization controller is connected to the left end of the TFBG aptamer sensor, and the right end of the TFBG aptamer sensor is connected to the spectrometer; the transmission optical fibers at both ends of the TFBG aptamer sensor are tightly clamped and fixed by optical fiber clamps 1 and 2, controlling the TFBG aptamer sensor to be suspended in the reaction chamber; the reaction chamber is fixed on the optical three-dimensional adjustment frame, which can be adjusted to control the height at which the TFBG aptamer sensor is suspended in the reaction chamber.

[0006] The TFBG aptor sensor structure is as follows: the sensor consists of a tilted fiber grating, a gold film layer, and a MUC1 aptor layer.

[0007] The steps of the quantitative detection method for exosomes based on aptamer-functionalized tilted fiber optic gratings combined with gold nanoparticle signal amplification are as follows.

[0008] Step 1: Fabricate the TFBG aptamer sensor.

[0009] First, using hydrogen-treated optical fiber, a tilted fiber grating is etched into the fiber core using a phase mask method, followed by annealing. Next, the tilted fiber grating is ultrasonically cleaned, and then a gold film layer with a thickness of 50 nm is deposited using magnetron sputtering. Then, the gold-plated TFBG is rinsed with deionized water at least three times, followed by immersion in a 20 μM MUC1 aptamer solution. The assembly is carried out at room temperature for 16 hours to form the MUC1 aptamer layer. After rinsing with deionized water and drying with nitrogen, the TFBG aptamer sensor is obtained and should be stored at 4°C for further use.

[0010] Step 2: Preparation of CD63 aptamer@gold nanoparticle solution.

[0011] 100 μL of a 10 μM CD63 aptamer was mixed with a 900 μM gold nanoparticle solution for 16 hours to obtain a CD63 aptamer@gold nanoparticle solution. The concentration of the gold nanoparticle solution used was 0.1 mg / mL, the gold nanoparticle size was 20 nm, and the final concentration of CD63 aptamer in the CD63 aptamer@gold nanoparticle solution was 1 μM.

[0012] Step 3: Exosome detection.

[0013] First, the TFBG aptamer sensor is firmly clamped and fixed using fiber optic clamps 1 and 2, suspending it approximately 2 mm above the reaction chamber. Incident light emitted from a broadband light source is transmitted via single-mode fiber to an electrically polarized controller, which adjusts the incident light to a P-polarization state. The P-polarized beam then reaches the TFBG aptamer sensor, and the transmission spectrum is obtained on a spectrometer. Next, the exosome solution to be tested is added to the reaction chamber and incubated for 10 minutes. The MUC1 aptamer layer captures the exosomes in the solution. The reaction chamber is then emptied, and a CD63 aptamer@gold nanoparticle solution is added again and incubated for another 10 minutes. In the first step, the gold nanoparticles aggregate on the surface of the TFBG aptamer sensor by binding to the CD63 aptamer on the exosomes, causing a change in the surface refractive index of the sensor. This change in refractive index is sensed by the TFBG aptamer sensor and ultimately reflected as a change in the transmission spectrum on the spectrometer. Secondly, the reaction chamber is cleaned with deionized water before testing with different concentrations of exosome sample solutions. Finally, the transmission spectrum data of different concentrations of exosome solutions recorded by the spectrometer are fitted to obtain the relationship between different exosome solution concentrations and transmission spectrum drift, enabling quantitative detection of exosomes. It is worth noting that the optical three-dimensional adjustment frame can also be used to lower the height of the reaction chamber so that the polarization state of light transmission in the TFBG aptamer sensor is not affected during cleaning of the reaction chamber or changing the test solution.

[0014] The working principle of the quantitative detection method for exosomes based on aptamer-functionalized tilted fiber optic gratings combined with gold nanoparticle signal amplification provided by this invention can be summarized as follows: When incident light is transmitted to the TFBG, it is completely reflected by the fiber sidewall, exciting an evanescent surface plasmon resonance wave on the surface of the gold film. P-polarized light enters the gold film, and the free electrons of the gold film interact with the P-polarized component of the light, generating a plasma wave. At the interface between the fiber and the gold film, plasma vibration forms a surface plasmon wave. When the horizontal component of the evanescent wave vector matches the wave vector of the surface plasmon wave and energy transfer occurs, the evanescent wave resonates with the surface plasmon wave, generating surface plasmon resonance. Light energy near the resonance wavelength is absorbed, resulting in a resonance trough in the output transmission spectrum. The MUC1 aptamer-exosome-CD63 aptamer@gold nanoparticle sandwich structure formed on the surface of the TFBG aptamer sensor causes a change in local refractive index, and the resonance trough and resonance wavelength also change. Therefore, the concentration of the exosome solution can be inferred by monitoring the shift or intensity change of the resonance wavelength.

[0015] The process of forming a MUC1 aptamer-exosome-CD63 aptamer@gold nanoparticle sandwich structure on the surface of the TFBG aptamer sensor is as follows: First, the TFBG aptamer sensor includes a tilted fiber grating, a gold film layer, and a MUC1 aptamer layer. During detection, the sensing area with the assembled MUC1 aptamer layer is directly immersed in the exosome sample solution to be tested. The MUC1 aptamer layer captures the exosomes in the sample, and the exosomes aggregate on the TFBG surface, forming the MUC1-exosome structure. Next, the TFBG aptamer sensor is immersed in a CD63 aptamer@gold nanoparticle solution. The exosomes on the sensor surface induce the gold nanoparticles to aggregate on the TFBG surface through the CD63 aptamer, forming the MUC1 aptamer-exosome-CD63 aptamer@gold nanoparticle sandwich structure. The aggregation of gold nanoparticles amplifies the refractive index change on the sensor surface. This refractive index change is sensed by the TFBG aptamer sensor and leads to a change in the output spectral signal, thus enabling the measurement of exosome sample solutions of different concentrations.

[0016] The beneficial effects of this invention are as follows: The TFBG aptamer sensor combines a fiber optic sensor and a biological aptamer on the same optical fiber to achieve specific separation and quantitative detection of exosomes, and has the advantages of miniaturization of fiber optic sensors, real-time monitoring, and low transmission loss; compared with antibodies, aptamers respond to exosomes more accurately and quickly, greatly reducing detection time and improving detection sensitivity; using dual aptamers, the specific MUC1 aptamer enables the detection of exosomes produced by a specific cancer cell line, and the use of the universal CD63 aptamer maximizes the signal amplification effect of gold nanoparticles; this platform can be integrated with a portable spectrometer to achieve point-of-care testing (POCT) or minimally invasive implantable continuous monitoring, breaking through the limitations of traditional SPR instruments that are large in size and fixed in use, and contributing to the early diagnosis and prognosis of clinical cancer. Attached Figure Description

[0017] Figure 1 This is a diagram of a quantitative exosome detection system based on aptamer-functionalized tilted fiber optic gratings combined with gold nanoparticle signal amplification.

[0018] Figure 2 (1) and (2) are the steps for fabricating the TFBG aptamer sensor, and (3) and (4) are schematic diagrams of the process for realizing quantitative detection of exosomes based on the TFBG aptamer sensor and the gold nanoparticle signal amplification system.

[0019] Figure 3 This is a spectral response diagram for detecting gradient concentration exosome solutions using this method.

[0020] Figure 4 According to Figure 3 Linear fitting plot of intensity variation and exosome concentration for the six selected envelope patterns.

[0021] Figure 5 According to Figure 4 Linear fitting plot of the response signals of Mode 2 and Mode 6 after intensity differential data processing. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Example 1: Fabrication of TFBG aptamer sensor.

[0024] In this embodiment, see Appendix Figure 1 Chinese illustrations, with Figure 1 The inset shows a TFBG aptamer sensor, comprising: a tilted fiber grating (51), a gold film layer (52), and a MUC1 aptamer layer (53).

[0025] See appendix Figure 2 In (1) and (2), the fabrication of the TFBG aptamer sensor (5) in the quantitative detection method for exosomes based on aptamer-functionalized tilted fiber optic grating combined with gold nanoparticle signal amplification provided by the present invention is as follows:

[0026] S1. Take a 20 mm optical fiber, use optical fiber strippers to strip off the coating layer of the optical fiber, leave 150 mm pigtails on each side, use a high-pressure hydrogenation reactor, set the pressure value to 15 MPa and the temperature to 75 °C, carry out hydrogen loading of the optical fiber, the hydrogen loading time is 14 days, and multiple optical fibers can be placed at one time.

[0027] S2. TFBG is etched using the phase mask method. The hydrogen-loaded photosensitive fiber is loaded into the fiber fixture of the fiber etching system, so that the stripes of the phase mask are at an angle of 8° to the axis of the photosensitive fiber. The precision displacement stage is controlled to etch the high-energy pulsed ultraviolet laser generated by the frequency-doubled argon ion laser onto the photosensitive fiber in the fiber structure through the phase mask, thus obtaining the tilted fiber grating (51).

[0028] S3. Place the etched tilted fiber grating into a high-temperature furnace for annealing. Set the temperature to 120°C and hold for 12 hours to eliminate stress and remove unbound hydrogen.

[0029] S4. Magnetron sputtering of a gold film on the surface of a TFBG: A high-vacuum magnetron sputtering fiber optic coating instrument was used. The target material was pure gold with a purity of 99.999%. An inclined fiber grating was installed on a customized fiber mold. The fiber mold platform can realize the revolution and rotation of the fiber in the sputtering chamber to ensure the uniform formation of the gold film during the sputtering process. The sputtering pressure was 0.5 Pa and the sputtering time was 100 s, resulting in a gold film with a thickness of 50 nm (52).

[0030] S5. Chemical assembly of the MUC1 aptamer layer on the TFBG surface gold film (53); the following assembly area is for the TFBG-SPR sensing area. First, prepare the MUC1 aptamer solution. The aptamer was purchased in dry powder form and existed as a dry film adhering to the tube wall. Centrifuge the test tube containing the aptamer at 4000 rpm for 1 minute to ensure that the film was deposited at the bottom of the tube, and then dissolve it in deionized water to obtain the aptamer solution. The concentration of the prepared aptamer solution can be calculated as follows: each centrifuge tube contains 2 nmoles of aptamer. Add 100 μL of ultrapure water to the aptamer dry powder test tube to obtain a 20 μM MUC1 aptamer solution. Then, take 100 μL of the 20 μM MUC1 aptamer solution and mix it with 100 μL of LTCEP (concentration of 20 μM). After reduction at room temperature for 2 hours, obtain the MUC1 aptamer solution with naked thiol groups. Finally, the fiber sensing area was immersed in the MUC1 aptamer solution for 16 hours. The MUC1 aptamer was self-assembled on the fiber surface by means of Au-S covalent bonds. After the process, it was cleaned with PBS, and the TFBG-aptamer sensor (5) was prepared. The sensor should be stored at 4°C for the next step of use.

[0031] Example 2: Construction of the detection platform.

[0032] In this embodiment, see Appendix Figure 1 It is a quantitative detection system for exosomes based on aptamer-functionalized tilted fiber optic gratings combined with gold nanoparticle signal amplification, including: a broadband light source (1), a single-mode fiber (2), an electric polarization controller (3), an optical fiber clamp 1 (4), a TFBG aptamer sensor (5), a reaction chamber (6), an optical three-dimensional adjustment frame (7), an optical fiber clamp 2 (8), and a spectrometer (9); the broadband light source (1) is connected to the input end of the electric polarization controller (3) through the single-mode fiber (2); the output end of the electric polarization controller (3) is connected to the TFBG aptamer sensor (5), a reaction chamber (6), an optical three-dimensional adjustment frame (7), an optical fiber clamp 2 (8), and a spectrometer (9); The left end of the FBG aptamer sensor (5) is connected to the spectral analyzer (9), and the right end of the TFBG aptamer sensor (5) is connected to the spectrometer (9). The transmission optical fibers at both ends of the TFBG aptamer sensor (5) are tightly clamped and fixed by optical fiber clamps 1 (4) and 2 (8) to control the TFBG aptamer sensor (5) to be suspended in the reaction chamber (6). The reaction chamber (6) is fixed on the optical three-dimensional adjustment frame (7), and the optical three-dimensional adjustment frame (7) can be adjusted to control the height of the TFBG aptamer sensor (5) suspended in the reaction chamber (6).

[0033] Example 3: Preparation of CD63 aptamer@gold nanoparticle solution.

[0034] First, a CD63 aptamer solution was prepared. The aptamer was purchased in dry powder form, adhering to the tube wall as a dry film. The test tube containing the aptamer was centrifuged at 4000 rpm for 1 minute to ensure the film deposited at the bottom of the tube. It was then dissolved in deionized water to obtain the aptamer solution. The concentration of the prepared aptamer solution was calculated as follows: each centrifuge tube contained 2 nmoles of aptamer. 100 μL of ultrapure water was added to the aptamer powder test tube to obtain a 20 μM CD63 aptamer solution. Then, 100 μL of the 20 μM CD63 aptamer solution was mixed with 100 μL of 20 μM LTCEP and reduced at room temperature for 2 h to obtain a CD63 aptamer solution with naked thiol groups. Finally, 100 μL of a 10 μM CD63 aptamer solution was mixed with 900 μM gold nanoparticle solution for 16 hours to obtain a CD63 aptamer@gold nanoparticle solution. The concentration of the gold nanoparticle solution used was 0.1 mg / mL, the particle size of the gold nanoparticles was 20 nm, and the final concentration of CD63 aptamer in the CD63 aptamer@gold nanoparticle solution was 1 μM.

[0035] Example 4: Detection of exosome gradient concentration solutions.

[0036] S1. Prepare exosome standard solutions by mixing 100 μg of commercially available lyophilized exosome powder (containing 1×10⁻⁶ exosomes) with lyophilized exosome powder. 12 Add 100 μL of PBS buffer to the particels to obtain a concentration of 10. 10 Exosome stock solution with particles / μL; then, using PBS buffer as a solvent, 10 μL of exosome stock solution was added to 990 μL of PBS buffer to obtain a concentration of 10. 7 The exosome solution was further serially diluted 10-fold using a pipette to obtain a final concentration of 10. 7 10 6 10 5 10 4 10 3 10 2 10 1 10 0 exosome gradient concentration solution of particles / μL.

[0037] S2. First, use fiber optic clamp 1 (4) and fiber optic clamp 2 (8) to firmly clamp and fix the TFBG aptamer sensor (5), so that it is suspended in the reaction chamber (6) at a height of about 2 mm. Then, use a pipette to add the exosome solution to be tested into the reaction chamber (6) and incubate for 10 min. The MUC1 aptamer layer (53) captures the exosomes in the exosome solution to be tested. Then, empty the reaction chamber (6) and add CD63 aptamer@gold nanoparticle solution into the reaction chamber (6) again and incubate for 10 min. Through the binding of exosomes with CD63 aptamer on the surface of gold nanoparticles, the gold nanoparticles are aggregated on the surface of the TFBG aptamer sensor (5), which further causes the surface refractive index of the TFBG aptamer sensor (5) to change. This refractive index change is sensed by the TFBG aptamer sensor (5) and is finally presented as a change in the transmission spectrum on the spectrometer (9).

[0038] Secondly, the transmission spectrum of the PBS solution was collected, and the signal representing the 0 concentration of exosomes was used as the baseline. Before changing to different concentrations of exosome sample solutions for detection, the reaction chamber was cleaned with deionized water (6). Then another set of test solutions was added, and the operation was repeated to complete the spectral acquisition in sequence and obtain the transmission spectra of the gradient concentration exosome solutions.

[0039] Finally, the transmission spectrum data of exosome solutions of different concentrations recorded by the spectrometer (9) are fitted to obtain the relationship between different exosome solution concentrations and transmission spectrum drift, thereby realizing the quantitative detection of exosomes. It is worth noting that the optical three-dimensional adjustment frame (7) can also be used to lower the height of the reaction chamber (6) so that the polarization state of light transmission in the TFBG aptamer sensor (5) is not affected during the cleaning of the reaction chamber (6) or the replacement of the test solution.

[0040] See appendix Figure 3 The figure shows the spectral response of gradient concentration exosome solutions detected using this method.

[0041] See appendix Figure 4 , for the basis Figure 3 Linear fitting plot of intensity variation and exosome concentration for the six selected envelope patterns.

[0042] See appendix Figure 5 , for the basis Figure 4 Linear fitting plot of the response signals of Mode 2 and Mode 6 after intensity differential data processing.

[0043] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0044] Those skilled in the art will readily understand that, according to the method of the present invention, various types of exosomes can be specifically, stably, and efficiently detected by changing the type of aptamer, and combinations and optimized designs can be made without conflicting technical features.

Claims

1. A method for quantitative detection of exosomes based on aptamer-functionalized tilted fiber optic gratings combined with gold nanoparticle signal amplification, characterized in that: The detection device consists of a broadband light source (1), a single-mode fiber (2), an electric polarization controller (3), a fiber clamp 1 (4), a TFBG aptamer sensor (5), a reaction chamber (6), an optical three-dimensional adjustment frame (7), a fiber clamp 2 (8), and a spectrometer (9). The broadband light source (1) is connected to the input end of the electric polarization controller (3) through the single-mode fiber (2). The output end of the electric polarization controller (3) is connected to the left end of the TFBG aptamer sensor (5), and the right end of the TFBG aptamer sensor (5) is connected to the spectrometer (9). The transmission fibers at both ends of the TFBG aptamer sensor (5) are tightly clamped and fixed by the fiber clamp 1 (4) and the fiber clamp 2 (8), which controls the TFBG aptamer sensor (5) to be suspended in the reaction chamber (6). The reaction chamber (6) is fixed on the optical three-dimensional adjustment frame (7), and the optical three-dimensional adjustment frame (7) can be adjusted to control the height of the TFBG aptamer sensor (5) suspended in the reaction chamber (6). The structure of the TFBG aptamer sensor (5) is as follows: the sensor consists of a tilted fiber grating (51), a gold film layer (52), and a MUC1 aptamer layer (53); The steps of the quantitative detection method for exosomes based on aptamer-functionalized tilted fiber optic gratings combined with gold nanoparticle signal amplification are as follows: Step 1: Fabrication of TFBG aptamer sensor (5); First, using hydrogen-treated photosensitive fiber, a tilted fiber grating (51) is etched in the fiber core using the phase mask method, followed by annealing; then, the tilted fiber grating (51) is ultrasonically cleaned, and then a gold film layer (52) is deposited using magnetron sputtering technology, with a thickness of 50 nm; then, the gold-plated TFBG is rinsed with deionized water at least 3 times, and then immersed in a 20 μM MUC1 aptamer solution, assembled at room temperature for 16 hours to form a MUC1 aptamer layer (53), cleaned with deionized water, and dried with nitrogen gas, thus obtaining the TFBG aptamer sensor (5), which should be stored at 4℃ for the next step of use; Step 2: Preparation of CD63 aptamer@gold nanoparticle solution; 100 μL of 10 μM CD63 aptamer was mixed with 900 μM gold nanoparticle solution for 16 hours to obtain CD63 aptamer@gold nanoparticle solution. The concentration of the gold nanoparticle solution used was 0.1 mg / mL, the particle size of the gold nanoparticles was 20 nm, and the final concentration of CD63 aptamer in the CD63 aptamer@gold nanoparticle solution was 1 μM. Step 3: Detection of exosomes; First, use fiber optic clamps 1 (4) and 2 (8) to firmly clamp and fix the TFBG aptamer sensor (5), suspending it in the reaction chamber (6) at a height of about 2 mm. The incident light emitted by the broadband light source (1) is transmitted through the single-mode fiber (2) to the electric polarization controller (3). The electric polarization controller (3) is used to adjust the incident light to the P polarization state. The P polarization state beam is transmitted to the TFBG aptamer sensor (5), and finally the transmission spectrum is obtained on the spectrometer (9); Then, the exosome solution to be tested is added to the reaction chamber (6) and incubated for 10 min. The MUC1 aptamer layer (53) captures the exosomes in the exosome solution to be tested. Then, the reaction chamber (6) is emptied, and the CD63 aptamer@gold nanoparticle solution is added to the reaction chamber (6) again and incubated for 10 min. In the first step, through the binding of exosomes with CD63 aptamers on the surface of gold nanoparticles, gold nanoparticles are aggregated on the surface of the TFBG aptamer sensor (5), further amplifying the surface refractive index change of the TFBG aptamer sensor (5). This refractive index change is sensed by the TFBG aptamer sensor (5) and ultimately presented as a change in the transmission spectrum on the spectrometer (9). Secondly, before changing to different concentrations of exosome sample solutions for detection, the reaction chamber (6) is cleaned with deionized water. Finally, the transmission spectrum data of different concentrations of exosome solutions recorded by the spectrometer (9) are fitted to obtain the relationship between different exosome solution concentrations and transmission spectrum drift, thereby realizing the quantitative detection of exosomes. It is worth noting that the optical three-dimensional adjustment frame (7) can also be used to lower the height of the reaction chamber (6) so that the polarization state of light transmission in the TFBG aptamer sensor (5) is not affected during the cleaning of the reaction chamber (6) or the replacement of the test solution.

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