Magneto-optical detection integrated rare earth fluorescent probe as well as preparation method and application thereof

Abstract

The invention discloses a magneto-optical detection integrated rare earth fluorescent probe as well as a preparation method and application thereof, and belongs to the technical field of nano luminescent materials, GdCl3. 6H2O and ErCl3. 6H2O are sequentially added into high-purity ethylene glycol, stirring is performed for 30 minutes until metal chloride is completely dissolved, NH4F is added into the high-purity ethylene glycol, stirring is performed until complete dissolution, an NH4F solution is dropwise added into a metal chloride solution, stirring is performed for 30 minutes, and the rare earth fluorescent probe is obtained. The method comprises the following steps: adding rare earth ions into a high-temperature furnace, intensely stirring for 30 minutes, pouring into a high-pressure kettle with a polytetrafluoroethylene lining for hydrothermal reaction, naturally cooling to room temperature, centrifugally washing, drying and annealing in the high-temperature furnace, thereby facilitating deep understanding of an influence mechanism of a magnetic field on fluorescence transition of the rare earth ions; and important experimental basis is provided for development of magnetic field regulation and control optical sensing devices, the magnetic field regulation and control optical sensing device has wide application prospects in the fields of magneto-optical sensing, biological imaging, information encryption, quantum storage and the like, and important support is provided for research and development of the magnetic field regulation and control optical sensing devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of nano-luminescent materials, and particularly relates to a rare-earth fluorescent probe integrating magneto-optical detection, and a preparation method and application thereof. Background Art

[0002] In recent years, due to their excellent optical properties and multifunctionality, rare-earth doped nano-materials have received extensive attention in the fields of optical sensing, bio-imaging, information storage, and quantum communication. Among them, rare-earth fluorescent probes have shown great application potential in fluorescence detection, disease diagnosis, magnetic resonance imaging (MRI) contrast agents, etc. due to their unique up-conversion (UC) and down-conversion (DC) luminescence properties. In up-conversion luminescence, nano-particles absorb two or more low-energy photons and emit a high-energy photon; while in down-conversion luminescence, nano-particles absorb a high-energy photon and emit two or more low-energy photons. However, in a complex environment, how to precisely control the luminescence properties of fluorescent probes to meet the detection requirements of high sensitivity and high stability remains one of the current research hotspots and challenges. The magneto-optical modulation technology can be used for high-precision sensing, non-contact detection, and magnetic-field-responsive bio-imaging applications by modulating optical signals with an external magnetic field. Especially during the energy-level transition process of rare-earth ions, the magnetic field can regulate the luminescence properties of rare-earth fluorescent probes by affecting electron orbital splitting (Zeeman effect) or changing the local crystal-field symmetry. Therefore, by combining the magneto-optical effect with rare-earth fluorescent probes and optimizing the doping concentration, nano-structure, and surface modification of rare-earth ions, the magneto-optical response can be significantly enhanced, the detection accuracy can be improved, and an integrated magneto-optical detection probe with both magnetic-field response and fluorescence detection functions can be developed, providing a new technical path for magnetically controllable optical sensing.

[0003] Compared with traditional dyes and quantum dot fluorescent probes, rare-earth fluorescent probes have longer luminescence lifetimes, narrower emission spectral bands, and lower autofluorescence interference, making them suitable for long-term imaging and high-sensitivity optical sensing. In addition, composite magnetic materials can endow the probes with magnetic field response capabilities, expanding their applications in magneto-optical modulation and magnetic field detection. Current research shows that the magnetic field can affect the luminescence intensity of rare-earth fluorescent probes by adjusting the transition probability or energy level splitting, realizing magnetic field sensing. Under periodic magnetic field changes, some materials may exhibit hysteresis effects, providing new technical support for magnetic storage and magnetic field measurement. In addition, the response characteristics of fluorescence with different wavelengths under magnetic field regulation may be different. Therefore, by optimizing the doping composition and material design, efficient magneto-optical modulation within a specific wavelength range can be achieved. The magneto-optical modulation technology combines the advantages of optics and magnetism and has broad application prospects in the fields of biomedical imaging, magnetic field imaging, high-resolution spectral detection, etc. For example, in biosensing, magneto-optical probes can be used for dual-modal detection to improve signal contrast; in magnetic field sensing, non-contact magnetic field measurement can be realized by measuring the change in fluorescence intensity. In addition, this technology also shows great potential in optical information encryption, quantum computing, and the development of high-sensitivity optical sensors. The current research on magneto-optical modulation rare-earth fluorescent probes is developing rapidly. Future key directions include optimizing material structures, enhancing magneto-optical responses, and integrating multiple functions to meet the requirements of higher precision, wider wavelength bands, and more stable magneto-optical detection. By further exploring new rare-earth doping systems, enhancing magnetic field regulation capabilities, and developing multi-mode detection technologies, this field is expected to make breakthrough progress in applications such as optical sensing, information storage, and magneto-optical imaging.

[0004] At present, the research on magneto-optical modulation fluorescent probes mainly focuses on systems based on rare-earth upconversion or downconversion luminescence. Er 3+ ions, as common rare-earth luminescence centers, can emit fluorescence at specific wavelengths under near-infrared (NIR) excitation. These luminescence characteristics will change under the action of a magnetic field, such as the modulation of spectral intensity and the fine-tuning of the emission peak position. Therefore, by optimizing the material preparation process and reasonably regulating the doping concentration and distribution of Er 3+ ions, the magneto-optical modulation effect can be further enhanced, and the sensitivity and stability of magneto-optical probes can be improved. Summary of the Invention

[0005] Technical problems to be solved:

[0006] Aiming at the deficiencies of the prior art, this application solves the technical problems of insufficient sensitivity and limited stability of existing magneto-optical probes, and provides a rare-earth fluorescent probe for integrated magneto-optical detection, its preparation method, and application.

[0007] Technical solutions:

[0008] To achieve the above object, the present application is realized through the following technical solutions:

[0009] A preparation method of a rare earth fluorescent probe integrating magneto-optical detection, specifically including the following steps:

[0010] First step: Weigh 97 - 99 mmol of GdCl3·6H2O and 1 - 3 mmol of ErCl3·6H2O of metal chlorides respectively with a high-precision electronic balance. Add the weighed metal chlorides GdCl3·6H2O and ErCl3·6H2O to 10 mL of high-purity ethylene glycol in sequence. Under the condition of magnetic stirring at 600 rpm, stir for 30 minutes until the metal chlorides are completely dissolved, the solution is in a transparent state and there are no any particulate matters, obtaining a metal chloride solution;

[0011] Second step: Weigh 4 mmol of NH4F with a high-precision electronic balance. Pour the weighed NH4F into a clean beaker, add 10 mL of high-purity ethylene glycol, and gently stir with a glass rod until NH4F is completely dissolved, forming a uniform and transparent solution, namely NH4F solution;

[0012] Third step: Use a clean dropper to suck the NH4F solution, and drop the NH4F solution into the metal chloride solution at a speed of 1 - 2 drops per second to obtain a precursor solution;

[0013] Fourth step: After all the NH4F solution is added dropwise, continue to stir for 30 minutes under the condition of 600 rpm to promote the full reaction of the components in the precursor solution and ensure the uniformity and stability of the precursor solution;

[0014] Fifth step: Install the polytetrafluoroethylene inner liner into the autoclave to ensure good sealing. Carefully pour the stable precursor solution into the autoclave with the polytetrafluoroethylene inner liner. Place the autoclave in a constant-temperature drying oven for hydrothermal reaction, and set the temperature to 200 °C and the reaction time to 3 hours;

[0015] Sixth step: After the hydrothermal reaction is completed, naturally cool to room temperature. Carefully transfer the reaction liquid in the autoclave to a clean centrifuge tube, centrifuge for 10 minutes under the centrifugation condition of 6000 rpm. After centrifugation, carefully pour off and discard the supernatant, and retain the precipitate at the bottom to separate the precipitate generated by the centrifugation reaction from the supernatant;

[0016] Seventh step: Add 25 mL of absolute ethanol to the precipitate in the centrifuge tube, shake well to ensure that the precipitate is completely wetted, and repeat the process of separating the precipitate by centrifuging at 6000 rpm for 10 minutes for 3 - 5 times until the centrifugation supernatant is completely clear and colorless;

[0017] Step 8: Transfer the centrifuged and washed precipitate to a clean glass dish or beaker, place it in an oven at 60 °C, and dry for 12 hours to ensure that the ethanol and moisture in the precipitate are completely volatilized. The dried precipitate should be in the form of a uniform powder;

[0018] Step 9: Gently grind the dried precipitate to make its particle size more uniform. Spread the powder evenly in a high-temperature resistant ceramic crucible, place the crucible in a high-temperature furnace, set the heating program, heat it to 400 °C at a rate of 5 °C per minute, and maintain a constant temperature at this temperature for 3 hours to complete the annealing process;

[0019] Step 10: After the annealing is completed, turn off the high-temperature furnace and let the sample cool naturally in the furnace for 3 - 5 hours. Carefully collect the annealed powder with clean forceps and sample bottles to finally obtain a high-purity Er 3+ -doped integrated magneto-optical detection rare earth fluorescent probe.

[0020] Furthermore, in the first step, 99 mmol of GdCl3·6H2O weighs 0.367 g, 1 mmol of ErCl3·6H2O weighs 0.0038 g, 97 mmol of GdCl3·6H2O weighs 0.36 g, and 3 mmol of ErCl3·6H2O weighs 0.011 g.

[0021] Furthermore, in the second step, 4 mmol of NH4F weighs 0.148 g.

[0022] Furthermore, during the dropping process in the third step, it should be ensured that the metal chloride solution is vigorously stirred at 600 rpm, and observe whether the solution is uniformly mixed to avoid the formation of precipitation due to excessive local concentration.

[0023] Furthermore, in the tenth step, the integrated magneto-optical detection rare earth fluorescent probe is characterized by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) for its morphology and crystal structure, and the fluorescence response of the integrated magneto-optical detection rare earth fluorescent probe under periodic magnetic field changes is measured.

[0024] This application also discloses an integrated magneto-optical detection rare earth fluorescent probe prepared by any of the above preparation methods.

[0025] An application of an integrated magneto-optical detection rare earth fluorescent probe in magneto-optical sensing, biological imaging, information encryption, and quantum storage.

[0026] Beneficial effects:

[0027] This application provides a preparation method of an integrated magneto-optical detection rare earth fluorescent probe. Compared with the prior art, it has the following

[0028] Beneficial effects:

[0029] 1. The present invention provides an integrated rare earth fluorescent probe for magneto-optical detection, which is prepared by a hydrothermal method and has a highly crystallized rod-shaped nanostructure with uniform element distribution and high purity. Energy dispersive X-ray spectroscopy (EDS) analysis shows that Gd, Er and F elements are uniformly distributed, confirming the high purity and doping uniformity of the material.

[0030] 2. In the characterization of optical properties, the fluorescence modulation ability of the probe under the condition of an external magnetic field was evaluated in detail using 808nm near-infrared light and 527nm visible light as excitation light sources. The probe of this application exhibited significant fluorescence modulation ability under 808nm and 527nm excitation light sources. Under 808nm excitation, 3% Er 3+ The luminescence intensity of the doped probe at 983nm decreased significantly with the increase of magnetic field strength, with the maximum decrease reaching 65.1%. When the magnetic field strength reached 1.3T, the fluorescence intensity dropped to 34.9% of the initial value. Under 527nm excitation, different emission wavelengths responded differently to the magnetic field. The decreasing trend of the emission intensity at 656nm and 842nm was relatively slow, while the decrease at 983nm was more significant. This emission wavelength-selective modulation characteristic provides a design basis for its use in multi-channel optical detection and band-tunable light sources.

[0031] 3. The fluorescence response of the rare earth fluorescent probe with integrated magneto-optical detection in the present application under the condition of periodic magnetic field changes. The results show that no hysteresis phenomenon occurs in the fluorescence intensity under either 808nm or 527nm excitation, and good repeatability is maintained over multiple magnetic field cycles, which indicates that the optical response of the probe in an external magnetic field environment is highly stable and repeatable, and can meet the stability requirements of magneto-optical detection equipment in long-term operation;

[0032] 4. The doping concentration of rare earth ions has a significant effect on the optical properties of the probe. 3+ The doping ratio of 3% Er was found 3+ When doped, the probe showed the best performance in the magneto-optical modulation experiment, with a high modulation depth and significantly improved sensitivity of the fluorescence intensity to the magnetic field. This result shows that the performance of the probe can be further optimized to meet the needs of different application scenarios through reasonable doping concentration design;

[0033] 5. This application has developed a set of highly sensitive magneto-optical detection experimental devices. Based on the integrated magneto-optical detection technology, with rare-earth fluorescent probes as the core sensing elements, through integrating a high-precision magnetic field control unit and multi-band excitation light sources and a series of optical elements, it realizes the precise control and measurement of magnetic-field-regulated luminescence, and is used to evaluate the comprehensive performance of the probes under different magnetic field intensities and excitation light conditions. This system can adapt to the fluorescence detection requirements at different excitation wavelengths, while ensuring the optical path stability and signal purity. The magnetic field intensity can be precisely regulated (such as in the range of 0 - 1.3 T), and the magnetic-field-induced fluorescence quenching or enhancement effect of the probes can be studied in real time; through time-division multiplexing and dynamic filtering technology, the efficient switching and signal separation of visible-near infrared multi-band excitation in a single system are realized for the first time, significantly improving the detection throughput; combined with the objective confocal design, the fluorescence collection efficiency is increased to more than 90%; this system can be equipped with a photomultiplier tube (PMT) to capture the fluorescence kinetic process at the microsecond level, providing unprecedented time resolution for the study of the magneto-optical response mechanism of rare-earth probes; this technological breakthrough not only promotes the basic research on the structure-activity relationship of magnetic nanomaterials, but also shows great application potential in in vivo biological magnetic labeling imaging and in-situ characterization of quantum sensor devices; it can complete the real-time detection of the fluorescence response of the probes under stable test conditions. This device provides important technical support for comprehensively characterizing the performance of magneto-optical probes, and also lays a solid foundation for subsequent application research;

[0034] 6. The magneto-optical detection integrated rare-earth fluorescent probe system prepared in this application has studied the optical modulation characteristics of the magneto-optical detection integrated rare-earth fluorescent probe under different magnetic field conditions. The research results not only help to deeply understand the influence mechanism of the magnetic field on the fluorescence transition of rare-earth ions, but also provide important experimental basis for the development of magnetic-field-regulated optical sensor devices. This probe has broad application prospects in the fields of magneto-optical sensing, biological imaging, information encryption, and quantum storage, and provides important support for the research and development of magnetic-field-regulated optical sensor devices. Description of the Drawings

[0035] Figure 1 These are the TEM and HRTEM images of the rare-earth fluorescent probe prepared by the hydrothermal method in Example 1 of this application. The left figure is the TEM image of the rare-earth fluorescent probe; the right figure is the HRTEM image of the rare-earth fluorescent probe;

[0036] Figure 2 These are the EDS element mapping distribution diagrams of the rare-earth fluorescent probe in Example 1 of this application. The upper left corner is the spatial overlap diagram of three elements, namely F, Er, and Gd, in the rare-earth fluorescent probe; the upper right corner is the spatial distribution diagram of the Gd element in the rare-earth fluorescent probe; the lower left corner is the spatial distribution diagram of the Er element in the rare-earth fluorescent probe; the lower right corner is the spatial distribution diagram of the F element in the rare-earth fluorescent probe;

[0037] Figure 3 For Example 3 of this application, the magneto-optical modulation diagram of the 1% Er 3+ rare-earth fluorescent probe after excitation by near-infrared light at 808 nm, where (a) is the emission spectrum of the rare-earth fluorescent probe under different magnetic fields under 808 nm laser excitation, and (b) is the dependence diagram of the normalized emission intensity on the magnetic field change after normalization of four characteristic peaks;

[0038] Figure 4 For the rare-earth fluorescent probe in Example 4 of this application, the magneto-optical modulation diagram after excitation by visible light at 527 nm under different magnetic fields, where (a) is the emission spectrum of the rare-earth fluorescent probe under different magnetic fields under 527 nm laser excitation, and (b) is the dependence diagram of the normalized emission intensity on the magnetic field change after normalization of three characteristic peaks;

[0039] Figure 5 For the test diagram of the magneto-optical detection stability ability of the fluorescent probe within the periodic change of the magnetic field in Example 5 of this application, where a is the change trend diagram of the normalized emission intensity at 983 nm and 546 nm of the rare-earth fluorescent probe within a complete magnetic field cycle under 808 nm laser excitation; b is the change trend diagram of the normalized emission intensity at 656 nm and 842 nm of the rare-earth fluorescent probe within a complete magnetic field cycle under 527 nm laser excitation;

[0040] Figure 6 For Example 6 of this application, the magneto-optical modulation diagram of the 3% Er 3+ rare-earth fluorescent probe after excitation by near-infrared light at 808 nm, where the upper figure is the emission spectrum of the 3% Er 3+ rare-earth fluorescent probe under different magnetic fields under 808 nm excitation, and the lower figure is the dependence diagram of the normalized emission intensity of the 983 nm characteristic peak of the 3% rare-earth fluorescent probe on the magnetic field change;

[0041] Figure 7 Schematic diagram of the magneto-optical detection experimental device of the rare-earth fluorescent probe in Examples 3-6 of this application. Detailed implementation mode

[0042] In order to more clearly elaborate the purpose, technical solution and its advantages of the present invention, the following will be described through specific examples. However, these examples are only used to explain the present invention and do not constitute any limitation to its patent scope. Without departing from the spirit and basic principles of the present invention, any modification, substitution or improvement should be regarded as a reasonable extension of the present invention and covered by its patent protection scope.

[0043] Example 1:

[0044] A preparation method of a 1% Er 3+ doped integrated rare-earth fluorescent probe for magneto-optical detection, specifically including the following steps:

[0045] Step 1: Weigh 0.367 g of GdCl3·6H2O, which is 99 mmol of metal chloride, and 0.0038 g of ErCl3·6H2O, which is 1 mmol of metal chloride, respectively, using a high-precision electronic balance. Add the weighed metal chlorides GdCl3·6H2O and ErCl3·6H2O to 10 mL of high-purity ethylene glycol in sequence. Under the condition of magnetic stirring at 600 rpm, stir for 30 minutes until the metal chlorides are completely dissolved, the solution becomes transparent and has no any particulate matter, obtaining a metal chloride solution;

[0046] Step 2: Weigh 0.148 g of NH4F, which is 4 mmol, using a high-precision electronic balance. Pour the weighed NH4F into a clean beaker, add 10 mL of high-purity ethylene glycol, and gently stir with a glass rod until NH4F is completely dissolved, forming a uniform and transparent solution, namely NH4F solution;

[0047] Step 3: Use a clean dropper to suck the NH4F solution, and drop the NH4F solution into the metal chloride solution at a rate of 1 - 2 drops per second, and keep stirring vigorously at 600 rpm to prevent local reaction precipitation, obtaining a precursor solution;

[0048] Step 4: After all the NH4F solution is added dropwise, continue to stir for 30 minutes under the condition of 600 rpm to promote the full reaction of the components in the precursor solution and ensure the uniformity and stability of the precursor solution;

[0049] Step 5: Install the polytetrafluoroethylene inner liner into the autoclave to ensure good sealing. Carefully pour the stable precursor solution into the autoclave with the polytetrafluoroethylene inner liner. Place the autoclave in a constant-temperature drying oven for hydrothermal reaction, set the temperature to 200 °C, and set the reaction time to 3 hours;

[0050] Step 6: After the hydrothermal reaction is completed, naturally cool to room temperature. Carefully transfer the reaction liquid in the autoclave to a clean centrifuge tube, centrifuge for 10 minutes under the centrifugation condition of 6000 rpm. After centrifugation, carefully pour off and discard the supernatant to separate the precipitate generated by the centrifugation reaction from the supernatant, and retain the precipitate at the bottom;

[0051] Step 7: Add 25 mL of absolute ethanol to the precipitate in the centrifuge tube, shake well to ensure that the precipitate is completely wetted. Repeat the process of centrifuging and separating the precipitate at 6000 rpm for 10 minutes 3 - 5 times until the centrifuged supernatant is completely clear and colorless, ensuring the removal of impurity ions and unreacted substances in the solution;

[0052] Step 8: Transfer the precipitate after centrifugal washing to a clean glass dish or beaker, place it in an oven at 60°C, and dry it for 12 hours to ensure that the ethanol and water in the precipitate are completely volatilized. The dried precipitate should be in a uniform powder state.

[0053] Step 9: Grind the dried precipitate gently to make its particle size more uniform, spread the powder evenly in a high-temperature resistant ceramic crucible, place the crucible in a high-temperature furnace, set the heating program, heat it up to 400°C at a rate of 5°C per minute, and keep it at this temperature for 3 hours to complete the annealing treatment;

[0054] Step 10: After annealing, turn off the high temperature furnace and let the sample cool naturally in the furnace for 4 hours. Use clean tweezers and sample bottles to carefully collect the annealed powder to finally obtain high-purity 1% Er. 3+ Doped rare earth fluorescent probe with integrated magneto-optical detection.

[0055] The nanoparticles obtained by the above steps were characterized by TEM. Figure 1 As shown in the figure, it is evenly dispersed in the matrix, in the shape of regular rods, with uniform size and smooth surface, indicating that the synthesis method is well controllable. HRTEM further reveals clear lattice fringes, and XPS analysis shows that the characteristic peaks of Gd, Er and F elements are obvious, and the distribution of each element is uniform, without impurity peaks, indicating that the sample has high purity and stable doping characteristics, such as Figure 2 These results prove that this material has good application prospects in the fields of magneto-optical modulation, optical sensing and bio-imaging.

[0056] Embodiment 2:

[0057] A 3% Er 3+ The preparation method of the doped rare earth fluorescent probe integrated with magneto-optical detection specifically comprises the following steps:

[0058] Step 1: Use a high-precision electronic balance to weigh 0.36 g of GdCl3·6H2O (97 mmol) and 0.011 g of ErCl3·6H2O (3 mmol) of metal chloride, respectively, and add the weighed metal chlorides GdCl3·6H2O and ErCl3·6H2O to 10 mL of high-purity ethylene glycol in sequence, and stir for 30 minutes under a magnetic stirring condition of 600 rpm until the metal chloride is completely dissolved, the solution is transparent and free of any particles, and a metal chloride solution is obtained;

[0059] Step 2: Use a high-precision electronic balance to weigh 0.148 g of 4 mmol of NH4F, pour the weighed NH4F into a clean beaker, add 10 mL of high-purity ethylene glycol, and gently stir with a glass rod until the NH4F is completely dissolved to form a uniform, transparent solution, i.e., NH4F solution;

[0060] Step 3: Use a clean dropper to suck up the NH4F solution, and drop the NH4F solution into the metal chloride solution at a rate of 1 - 2 drops per second, while vigorously stirring at 600 rpm to prevent local reaction precipitation, to obtain a precursor solution;

[0061] Step 4: After all the NH4F solution has been dropped, continue to stir for 30 minutes at 600 rpm to promote the full reaction of the components in the precursor solution and ensure the uniformity and stability of the precursor solution;

[0062] Step 5: Install the polytetrafluoroethylene inner liner into the autoclave, ensure good sealing, carefully pour the stable precursor solution into the autoclave with the polytetrafluoroethylene inner liner, place the autoclave in a constant temperature drying oven for hydrothermal reaction, set the temperature to 200 °C, and set the reaction time to 3 hours;

[0063] Step 6: After the hydrothermal reaction is completed, naturally cool to room temperature, carefully transfer the reaction liquid in the autoclave to a clean centrifuge tube, centrifuge for 10 minutes under the centrifugation condition of 6000 rpm. After centrifugation, carefully pour off and discard the supernatant, separate the precipitate formed by the centrifugation reaction from the supernatant, and retain the precipitate at the bottom;

[0064] Step 7: Add 25 mL of anhydrous ethanol to the precipitate in the centrifuge tube, shake well to ensure that the precipitate is completely wetted, repeat the process of separating the precipitate by centrifuging at 6000 rpm for 10 minutes 3 - 5 times until the centrifuged supernatant is completely clear and colorless, to ensure the removal of impurity ions and unreacted substances in the solution;

[0065] Step 8: Transfer the centrifuged and washed precipitate to a clean glass dish or beaker, place it in an oven at 60 °C, and dry for 12 hours to ensure that the ethanol and water in the precipitate are completely volatilized. The dried precipitate should be in the form of a uniform powder;

[0066] Step 9: Gently grind the dried precipitate to make its particle size more uniform, evenly spread the powder in a high-temperature resistant ceramic crucible, place the crucible in a high-temperature furnace, set the heating program, heat it to 400 °C at a rate of 5 °C per minute, and maintain a constant temperature at this temperature for 3 hours to complete the annealing treatment;

[0067] Step 10: After the annealing is completed, turn off the high-temperature furnace and let the sample cool naturally in the furnace for 4 hours. Carefully collect the annealed powder with clean tweezers and sample bottles, and finally obtain a high-purity 3% Er 3+ doped magneto-optical detection integrated rare earth fluorescent probe.

[0068] Example 3:

[0069] Magneto-optical modulation of the rare earth fluorescent probe after excitation by near-infrared light at 808 nm under an external magnetic field:

[0070] The experimental results show that, as Figure 3 shown, using an 808 nm continuous laser as the excitation source, the emission spectra of GdF3:Er 3+ nanoparticles under different magnetic fields were measured by gradually increasing the coil current. To more clearly compare the changes in the emission intensities of the four different peaks, the emission intensities of each peak were normalized with the peak emission intensity without a magnetic field. As the magnetic field increases, the emission intensity shows a trend of first decreasing and then increasing. When the applied magnetic field reaches 0.89 T, the emission intensities at each wavelength decrease to the lowest values; at 1.3 T, the emission intensities decrease to 44.5%, 48.7%, 52.5%, and 80.1% of the original values. It can be seen that the upconversion luminescence (528, 546, 656 nm) decays faster than the downconversion luminescence (983 nm), and the suppression effect is more significant. This phenomenon can be attributed to the magneto-optical modulation effect: as the applied magnetic field increases, the energy levels of Er 3+ ions undergo Zeeman splitting, and the transition probabilities between energy levels are significantly affected. This effect is more obvious in the upconversion process because the upconversion process usually involves multi-photon absorption and energy transfer steps, which are more sensitive to small changes in energy levels. In addition, the observed trends in the emission intensities of different wavelengths in the experiment also indicate that the emission spectrum of rare-earth fluorescent probes can be precisely regulated by applying an external magnetic field, making it a potential magneto-optical modulation material.

[0071] Example 4:

[0072] The difference between this Example 4 and Example 3 is only that the excitation light source is changed from an 808 nm continuous laser to a 527 nm Q-switched laser pulse, the same rare-earth fluorescent probe is used, and other conditions remain unchanged. Magneto-optical modulation of the rare-earth fluorescent probe under an external magnetic field after excitation by near-infrared light at 527 nm.

[0073] The experimental results show that the research on the magnetic field suppression of the emission between two adjacent states 3+ in Er 2 H 11 / 2 and 4 S 3 / 2 luminescence in Er nanocrystals mainly focuses on the green emissions at 528 nm and 546 nm. As Figure 4 shown, using a 527 nm Q-switched laser pulse to excite 4 I 15 / 2 → 2 H 11 / 2Transitions, down-conversion luminescence was observed. The luminescence spectra recorded at different magnetic field strengths and the normalization results of the luminescence intensities of the three luminescence peaks under non-magnetic field excitation are shown. It can be seen that as the magnetic field strength increases, the luminescence intensities at the three wavelengths all show a trend of first decreasing slowly and then rapidly. When the magnetic field reaches 1.3 T, the luminescence intensities at 656, 842, and 983 nm decrease to about 66.7%, 67.5%, and 66.2% of the initial values, respectively, indicating that Zeeman splitting causes 2 H 11 / 2 the reduction of the excited state population, thus causing luminescence inhibition. Since the low excited state population mainly comes from relaxation, the observed inhibition effect on the luminescence peaks has the same characteristics. This significant magneto-optical modulation property of the rare earth fluorescent probe under an external magnetic field provides new possibilities for spectral regulation and information processing.

[0074] Example 5:

[0075] The magneto-optical detection stability of the fluorescent probe under periodic magnetic field changes:

[0076] The experimental results show that, as Figure 5 shown, the normalized luminescence intensities at 983 and 546 nm after a complete cycle of the magnetic field under 808 nm laser excitation were measured, and no hysteresis phenomenon was observed. Similar phenomena were also observed at wavelengths 528 and 656 nm. The normalized luminescence intensities at 656 and 842 nm after a complete cycle of the magnetic field under 527 nm laser excitation were measured, and no hysteresis phenomenon was observed. Similar phenomena were also observed at wavelength 983 nm. These results indicate that the rare earth fluorescent probe exhibits excellent magneto-optical detection stability under periodic magnetic field changes. This property is particularly crucial for high-precision optical detection and real-time monitoring in a dynamic magnetic field environment. The stable response formed by the coupling of the electronic structure of rare earth ions and the magnetic field is the core factor for realizing periodic magnetic field regulation, and at the same time verifies the application potential of this material under complex light-magnetic coupling conditions.

[0077] Example 6:

[0078] The difference between this Example 6 and Example 3 is only that the concentration of Er 3+ is changed from 1% to 3%, and other conditions remain unchanged. The magneto-optical modulation of the 3% Er 3+ rare earth fluorescent probe after excitation by near-infrared light at 808 nm:

[0079] The experimental results show that, as Figure 6 shown, using an 808 nm continuous laser as the excitation source, the 3% Er 3+Emission spectrum of the nanoparticles. To observe the change in luminescence intensity more clearly, the luminescence intensity at 983 nm was normalized by the peak luminescence intensity without magnetic field. As the magnetic field increased, the luminescence intensity showed a trend of first decreasing slowly and then rapidly. When the applied magnetic field reached 1.3 T, the luminescence intensity decreased to 34.9% of the original value. In the experiment, 3% Er 3+ The selection of concentration is particularly crucial. Its moderate doping ratio effectively avoids the concentration quenching effect caused by high-concentration doping and ensures significant magneto-optical response characteristics. This concentration optimization demonstrates the potential of Er 3+ ions to regulate the optical behavior in an applied magnetic field, laying a foundation for the development of efficient rare-earth fluorescence probes.

[0080] Example 7

[0081] As Figure 7As shown in the figure, this application studies and constructs a set of high-sensitivity magneto-optical detection experimental device. This device is based on the integrated technology of magnetic-optical detection, with rare-earth fluorescent probes as the core sensing elements. Through the integration of a high-precision magnetic field control unit (electromagnet and magnetic field controller) and multi-band excitation light sources (808nm continuous-wave laser and 527nm pulsed laser), and through a series of optical elements, precise control and measurement of magnetic-field-regulated luminescence are achieved. It is used to evaluate the comprehensive performance of the probe under different magnetic field intensities and excitation light conditions. The device includes a high-sensitivity spectrometer, multi-band excitation light sources, and a precise magnetic field control unit; it includes optical modules such as high-reflection mirrors (M1), beam splitters (BS1, BS2), and 10x objective lenses (OB), which are focused on the surface of the fluorescent probe placed in the magnetic field. When excited by an 808nm continuous-wave laser, the emitted fluorescence is collected by the objective lens (OB), and after passing through the beam splitter (BS1), a band-pass filter (F1, central wavelength 800nm), and a focusing lens (L1, focal length 30mm), it is collected by an optical fiber spectrometer (OceanOptics MayaPro), realizing the dynamic collaborative regulation of the magnetic field and the optical field. For 527nm laser excitation, the collection path of the fluorescence signal is similar. When F1 is replaced by a long-pass filter (F2, cut-off wavelength 550nm), the spectral data is processed and analyzed by a computer. This system can adapt to the fluorescence detection requirements at different excitation wavelengths, while ensuring the stability of the optical path and the purity of the signal. The magnetic field intensity can be precisely regulated (such as in the range of 0 - 1.3T), and the magnetic-field-induced fluorescence quenching or enhancement effect of the probe can be studied in real time. It solves the problems of poor magnetic-field-optical-field synergy, insufficient multi-band excitation compatibility, and difficulty in extracting weak signals in traditional magneto-optical detection. The innovations are as follows: 1. Through time-division multiplexing and dynamic filtering technology, for the first time, efficient switching and signal separation of visible-near-infrared multi-band excitation within a single system are realized, significantly improving the detection throughput; 2. Combining the objective lens confocal design, the fluorescence collection efficiency is increased to more than 90%; 3. This system can be paired with a photomultiplier tube (PMT) to capture the fluorescence kinetic process at the microsecond level, providing unprecedented time resolution for the study of the magneto-optical response mechanism of rare-earth probes. This technological breakthrough not only promotes the basic research on the structure-activity relationship of magnetic nanomaterials, but also shows great application potential in in vivo biological magnetic labeling imaging and in-situ characterization of quantum sensor devices. It can complete the real-time detection of the fluorescence response of the probe under stable test conditions. This device provides important technical support for comprehensively characterizing the performance of magneto-optical probes, and also lays a solid foundation for subsequent application research

[0082] The above has made an exemplary description of the present invention. It should be noted that without departing from the core of the present invention, any simple deformation, modification, or equivalent substitution that can be made by those skilled in the art without creative labor falls within the protection scope of the present invention

Claims

1. A preparation method of a rare earth fluorescent probe integrating magneto - optical detection, characterized in that, Specifically, it includes the following steps: The first step: Weigh 97 - 99 mmol of GdCl3·6H2O and 1 - 3 mmol of ErCl3·6H2O of metal chlorides respectively with a high-precision electronic balance. Add the weighed metal chlorides GdCl3·6H2O and ErCl3·6H2O to 10 mL of high-purity ethylene glycol in sequence. Under the condition of magnetic stirring at 600 rpm, stir for 30 minutes until the metal chlorides are completely dissolved, the solution becomes transparent and has no any particulate matter, obtaining a metal chloride solution; The second step: Weigh 4 mmol of NH4F with a high-precision electronic balance. Pour the weighed NH4F into a clean beaker, add 10 mL of high-purity ethylene glycol, and gently stir with a glass rod until NH4F is completely dissolved, forming a uniform and transparent solution, namely NH4F solution; The third step: Use a clean dropper to suck the NH4F solution, and add the NH4F solution drop by drop to the metal chloride solution at a speed of 1 - 2 drops per second to obtain a precursor solution; The fourth step: After all the NH4F solution is added dropwise, continue to stir for 30 minutes under the condition of 600 rpm to promote the full reaction of the components in the precursor solution and ensure the uniformity and stability of the precursor solution; The fifth step: Install the polytetrafluoroethylene inner liner into the autoclave to ensure good sealing. Carefully pour the stable precursor solution into the autoclave with the polytetrafluoroethylene inner liner. Place the autoclave in a constant-temperature drying oven for hydrothermal reaction, set the temperature to 200 °C, and set the reaction time to 3 hours; The sixth step: After the hydrothermal reaction is completed, naturally cool to room temperature. Carefully transfer the reaction liquid in the autoclave to a clean centrifuge tube, centrifuge for 10 minutes under the centrifugation condition of 6000 rpm. After centrifugation, carefully pour off and discard the supernatant, retain the precipitate at the bottom, and separate the precipitate generated by the centrifugation reaction from the supernatant; The seventh step: Add 25 mL of anhydrous ethanol to the precipitate in the centrifuge tube, shake well to ensure that the precipitate is completely wetted. Repeat the process of centrifuging the precipitate for 10 minutes at 6000 rpm for 3 - 5 times until the centrifuged supernatant is completely clear and colorless; The eighth step: Transfer the centrifuged and washed precipitate to a clean glass dish or beaker, place it in an oven at 60 °C, and dry for 12 hours to ensure that the ethanol and water in the precipitate are completely volatilized. The dried precipitate should be in the form of uniform powder; The ninth step: Gently grind the dried precipitate to make its particle size more uniform. Spread the powder evenly in a high-temperature-resistant ceramic crucible. Place the crucible in a high-temperature furnace, set the heating program, heat it to 400 °C at a rate of 5 °C per minute, and keep it at this temperature for 3 hours to complete the annealing treatment; Step 10: After annealing is completed, turn off the high-temperature furnace and let the sample cool naturally in the furnace for 3 - 5 hours. Carefully collect the annealed powder with clean forceps and sample bottles to finally obtain a highly pure Er 3+ -doped integrated magneto-optical detection rare earth fluorescence probe.

2. The preparation method of the magneto-optical detection integrated rare earth fluorescence probe according to claim 1, characterized in that, In the first step, 99 mmol of GdCl3·6H2O weighs 0.367 g, 1 mmol of ErCl3·6H2O weighs 0.0038 g, 97 mmol of GdCl3·6H2O weighs 0.36 g, and 3 mmol of ErCl3·6H2O weighs 0.011 g.

3. The preparation method of the magneto-optical detection integrated rare earth fluorescent probe according to claim 1, wherein: In the second step, 4 mmol of NH4F weighs 0.148 g.

4. The preparation method of the magneto-optical detection integrated rare earth fluorescence probe according to claim 1, characterized in that: During the third-step dropping process, it should be ensured that the metal chloride solution is vigorously stirred under the condition of 600 rpm, and observe whether the solution is evenly mixed to avoid the formation of precipitation due to excessive local concentration.

5. The preparation method of the magneto-optical detection integrated rare earth fluorescence probe according to claim 1, characterized in that: In the tenth step, the magneto-optical detection integrated rare-earth fluorescence probe is characterized by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy HRTEM to characterize its morphology and crystal structure, and measure the fluorescence response of the magneto-optical detection integrated rare-earth fluorescence probe under the condition of periodic magnetic field change.

6. A magneto-optical detection integrated rare-earth fluorescence probe prepared by the preparation method according to any one of claims 1-5.

7. Use of the magneto-optical detection integrated rare-earth fluorescence probe according to claim 6 in magneto-optical sensing, bioimaging, information encryption and quantum storage.

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