Photoinduced regeneration rare earth fluorescent microsensor with coronavirus-like structure, and synthesis method and application of photoinduced regeneration rare earth fluorescent microsensor

Abstract

The invention relates to a photoinduced regeneration rare earth fluorescent microsensor similar to a coronavirus structure. The photoinduced regeneration rare earth fluorescent microsensor comprises SiO2 microspheres, a lanthanide metal (Ln)-cyclodextrin (CD) coordination layer and Ag2O nanoparticles, wherein the SiO2 microsphere is an inner core, the SiO2 microsphere is coated with the lanthanide series metal-cyclodextrin coordination layer, and the Ag2O nanoparticles are loaded on the coordination layer. The invention further relates to a synthesis method and application of the photoinduced regeneration rare earth fluorescent microsensor.

Description

Technical Field

[0001] This invention relates to a photo-induced regeneration rare-earth fluorescent microsensor with a coronavirus-like structure, its synthesis method, and its applications. Background Technology

[0002] Tetracyclines (TCs), as broad-spectrum antibiotics, have been widely used in poultry, aquaculture, and for treating personal infections due to their low cost, high efficacy, and low toxicity. However, the abuse of TCs has led to a significant increase in immune system depletion and the emergence of drug-resistant bacteria, posing a major challenge to public health. In response to the increasing antibiotic residues in the environment and food, global attention has focused on stricter limits (e.g., in EU Regulation 675 / 92, the maximum residue limit for TCs in milk is 100 μg / kg). -1 To date, various high-sensitivity sensing strategies have been proposed for detecting antibiotic residues, including electrochemical sensors based on MOFs or MIPs, fluorescence sensors based on QDs or Ln, and colorimetric sensors. However, these sensors also have some limitations, such as high specificity for single analyte identification and the fact that most sensors can only be used once, resulting in low utilization efficiency, high operating costs, significant material waste, and potential environmental problems.

[0003] Therefore, new detection sensors still need to be developed, especially for tetracycline antibiotics. Summary of the Invention

[0004] One aspect of this invention provides a photo-induced regenerated rare-earth fluorescent microsensor with a structure similar to that of a coronavirus, wherein the photo-induced regenerated rare-earth fluorescent microsensor comprises SiO2 microspheres, a lanthanide (Ln)-cyclodextrin (CD) coordination layer and Ag2O nanoparticles; wherein the SiO2 microspheres are the core, the lanthanide-cyclodextrin coordination layer coats the SiO2 microspheres, and the Ag2O nanoparticles are loaded on the coordination layer.

[0005] Another aspect of the present invention provides a method for synthesizing a photo-regenerated rare-earth fluorescent microsensor with a coronavirus-like structure, comprising the following steps:

[0006] (1) Dissolve cyclodextrin and lanthanide metal salts in ultrapure water, sonicate and stir at room temperature to form a mixed solution; then gradually add powdered SiO2 to the mixed solution in batches and grind until dry; heat, wash and vacuum dry the resulting solid to obtain powdered SiO2@CD-Ln;

[0007] (2) Disperse powdered SiO2@CD-Ln in ultrapure water, slowly add silver nitrate solution to form a suspension, filter the suspension, wash the filter, heat and dry to obtain powdered SiO2@CD-Ln@Ag2O.

[0008] In another aspect, the present invention provides the use of a photo-induced regenerated rare-earth fluorescent microsensor with a coronavirus-like structure for detecting tetracycline antibiotic residues in the environment, food, and traditional Chinese medicine.

[0009] This invention utilizes silica as a carrier and employs a hydrothermal coordination-coprecipitation method to prepare a photorenewable fluorescent sensing material, SiO2@CD-Ln@Ag2O. This material exhibits unique fluorescence sensing and photoregeneration properties, enhancing the absorption of Ln metal ions (especially Eu) through CD, particularly β-CD or modified β-CD (especially carboxylic acid-modified CD). 3+ The material's binding ability to tetracycline antibiotics (TCs) allows it to enhance specific fluorescence response through host-guest interactions. Simultaneously, the Ag₂O loaded on the material surface exhibits excellent visible-light photocatalytic degradation capabilities; the reactive oxygen species (ROS) generated by visible-light excitation effectively degrade TCs, enabling the sensing site to recover and achieve a reversible fluorescence signal response. Furthermore, SiO₂, as a stable inorganic support, not only improves the material's dispersibility and stability but also provides an ideal loading platform for the fluorescent Ln metal ions and the catalytically active component Ag₂O, ensuring the structural integrity of the material during recycling. The material of this invention exhibits excellent performance in fluorescence sensing and photocatalytic degradation, including a low limit of detection (LOD), a wide linear range (i.e., detection range), and maintains stable fluorescence intensity and efficient detection capability for tetracycline antibiotics even after multiple cycles, demonstrating excellent renewability and durability. Attached Figure Description

[0010] Figure 1 The images include: (a) a schematic diagram of the synthesis of the material of the present invention; (b) the XPS full spectrum of SiO2@β-CD-Eu@Ag2O of the material of the present invention; (c) the high-resolution XPS image of Ag 3d in SiO2@β-CD-Eu@Ag2O of the material of the present invention; (d) the high-resolution XPS image of Eu 3d; (e) the high-resolution XPS image of C1s; (f) the XRD pattern of SiO2@β-CD-Eu@Ag2O of the material of the present invention; (g) the SEM image of SiO2@β-CD-Eu@Ag2O of the material of the present invention; (h) the TEM image of SiO2@β-CD-Eu of the material of the present invention; (i) the TEM image of SiO2@β-CD-Eu@Ag2O of the material of the present invention; (j) the EDX image of a single SiO2@β-CD-Eu@Ag2O; and (k) the HRTEM image of SiO2@β-CD-Eu@Ag2O of the material of the present invention.

[0011] Figure 2Includes (a) the FTIR spectrum of the material SiO2@β-CD-Eu@Ag2O of the present invention and (b) the Raman spectrum of the material SiO2@β-CD-Eu@Ag2O of the present invention.

[0012] Figure 3 This includes (a) fluorescence spectra of materials SiO2@Eu2O3, SiO2@β-CD-Eu, and the present invention's SiO2@β-CD-Eu@Ag2O before and after the addition of TC; (b) the effect of ultrasonic time on the fluorescence intensity of the present invention's SiO2@β-CD-Eu@Ag2O after binding with TC; (c) the response of pH value to the fluorescence intensity of the present invention's SiO2@β-CD-Eu@Ag2O after binding with TC; and (d) 0.2 mg / mL -1 Fluorescence response of SiO2@β-CD-Eu concentration to TC; (e) 0.5 mg mL -1 Fluorescence response of SiO2@β-CD-Eu concentration to TC; (f) 1.0 mg mL -1 Fluorescence response of SiO2@β-CD-Eu concentration to TC; (g) 0.5 mg mL -1 The fluorescence response of the material SiO2@β-CD-Eu@Ag2O to TC is shown in the following figures: (h) Fluorescence response of the material SiO2@β-CD-Eu@Ag2O to TC under different interfering conditions; (i) Color change of the material SiO2@β-CD-Eu@Ag2O to various antibiotics under ultraviolet light (365nm); (j) Fluorescence response of the material SiO2@β-CD-Eu@Ag2O to TCH; (k) Fluorescence response of the material SiO2@β-CD-Eu@Ag2O to CTCH; (l) Fluorescence response of the material SiO2@β-CD-Eu@Ag2O to OTC.

[0013] Figure 4 The figures include (a) a graph showing the degradation performance of the material SiO2@β-CD-Eu@Ag2O of the present invention on tetracycline under different light conditions; (b) a graph showing the reusability of the material SiO2@β-CD-Eu@Ag2O of the present invention on TC; (c) degradation graphs of four antibiotics after spiking under different light conditions; and (d) a graph showing the fluorescence repeatability of the material SiO2@β-CD-Eu@Ag2O of the present invention on TC.

[0014] Figure 5The diagram includes (a) UV-Vis absorption spectra of TC, SiO2@Eu2O3, and SiO2@Eu2O3+TC; (b) fluorescence emission spectra of SiO2@Eu2O3 and SiO2@Eu2O3+TC; (c) UV absorption spectra of TC and TC+β-CD; (d) optimized binding model diagram of Eu2O3-TC-Ag2O; and (e) degradation mechanism diagram. Detailed Implementation

[0015] This invention provides a photo-regenerated rare-earth fluorescent microsensor with a structure similar to that of a coronavirus, wherein the photo-regenerated rare-earth fluorescent microsensor comprises SiO2 microspheres, a lanthanide (Ln)-cyclodextrin (CD) coordination layer and Ag2O nanoparticles; wherein the SiO2 microspheres are the core, the lanthanide-cyclodextrin coordination layer coats the SiO2 microspheres, and the Ag2O nanoparticles are loaded on the coordination layer.

[0016] In one embodiment of the invention, the lanthanide metal is selected from Eu, Gd, Tb and Dy, with Eu being preferred.

[0017] In one embodiment of the invention, the cyclodextrin is selected from β-cyclodextrin or β-cyclodextrin modified with the following groups: carboxylic acid group, phenolic hydroxyl group, alcoholic hydroxyl group, phosphate group (-PO4H2 or -PO4). 2- The group may consist of an amino group (-NH2) and a thiol group (-SH), preferably a carboxylic acid group. The carboxylic acid is selected from monocarboxylic acids, such as acetic acid, propionic acid, and butyric acid. Cyclodextrins, such as acetic acid-modified β-cyclodextrins, may be solvates, such as ethanolates. The solvates are typically formed by combining the solvent used in the preparation of carboxylic acid-modified β-cyclodextrins from β-cyclodextrins.

[0018] In this invention, the SiO2 microspheres coated with the lanthanide metal-cyclodextrin coordination layer are simply referred to as SiO2@CD-Ln, where CD-Ln represents the lanthanide metal-cyclodextrin coordination layer and SiO2 represents the core of the SiO2 microspheres.

[0019] In this invention, the photoinduced regenerated rare earth fluorescent microsensor is simply referred to as SiO2@CD-Ln@Ag2O, where Ag2O represents the supported Ag2O nanoparticles, CD-Ln represents the lanthanide metal-cyclodextrin coordination layer, and SiO2 represents the SiO2 microsphere core.

[0020] The present invention also provides a method for synthesizing the aforementioned photoinduced regenerated rare-earth fluorescent microsensor, comprising the following steps:

[0021] (1) Dissolve cyclodextrin and lanthanide metal salts in ultrapure water, sonicate and stir at room temperature to form a mixed solution; then gradually add powdered SiO2 to the mixed solution in batches and grind until dry; heat, wash and vacuum dry the resulting solid to obtain powdered SiO2@CD-Ln;

[0022] (2) Disperse powdered SiO2@CD-Ln in ultrapure water, slowly add silver nitrate solution to form a suspension, filter the suspension, wash the filter, heat and dry to obtain powdered SiO2@CD-Ln@Ag2O.

[0023] In step (1) of this invention, the Z-average particle size of the powdered SiO2 is in the range of 180-240 nm, as determined by dynamic light scattering. A suitable particle size can be obtained by grinding the powdered SiO2 in an agate mortar. The mixture is then sonicated at room temperature for 30-60 min at 500-800 rpm. -1 Stir for 2-6 hours to ensure adequate coordination of the cyclodextrin with the lanthanides. Heating of the resulting solid can be performed in an oven, typically at 110-125°C for 5-12 hours. The product is washed with ultrapure water and ethanol, and then vacuum dried at 40-50°C for 2-6 hours to obtain the final product.

[0024] In step (2) of the present invention, SiO2@β-CD-Eu and silver nitrate solution can be stirred to fully form a homogeneous suspension. The stirring is usually 300-500 r / min. -1 The process is carried out for 1-2 hours. The filtrate is washed with 95% ethanol and anhydrous ethanol. Heating can be carried out in an oven, usually at 110-125°C for 5-12 hours, to obtain the product.

[0025] In one embodiment of the invention, the cyclodextrin is a carboxylic acid, particularly acetic acid, and the modified β-cyclodextrin is obtained as follows:

[0026] Under alkaline conditions and heating, β-cyclodextrin was reacted with the sodium salt of monochlorocarboxylic acid (e.g., chloroacetic acid, 2-chloropropionic acid) in ultrapure water overnight. After the reaction solution was cooled to room temperature, the pH was adjusted to 3-5, and a mixed solution of methanol and ethanol was added until the precipitate was completely formed. The white precipitate was collected, washed, and dried to obtain powdered carboxylic acid-modified β-cyclodextrin.

[0027] In one embodiment of the present invention, the cyclodextrin is acetic acid-modified β-cyclodextrin, which is obtained as follows: under alkaline conditions and heating, β-cyclodextrin and sodium chloroacetate are reacted overnight in ultrapure water. After the reaction solution is cooled to room temperature, the pH is adjusted to 3-5, and a mixed solution of methanol and ethanol is added until the precipitate is completely precipitated. The white precipitate is collected, washed, and dried to obtain white powdered acetic acid-modified β-cyclodextrin (β-CD-CH2COOH·2C2H5OH).

[0028] In the preparation of carboxylic acid-modified β-cyclodextrin, alkaline conditions can be adjusted with NaOH, and the mixture is heated at 80-90℃ and stirred for 1-2 hours. The pH can be adjusted to 3-5 with concentrated HCl. Methanol and ethanol are mixed in a 1:2-3 (v / v) ratio to form a mixed solution. A precipitate is formed by stirring, and the white precipitate is collected by vacuum filtration. The precipitate is washed with methanol and anhydrous ethanol and then dried under vacuum at 40-50℃ for 2-3 hours to obtain powdered carboxylic acid-modified β-cyclodextrin.

[0029] In one embodiment of the invention, the lanthanide metal salt is its water-soluble salt, such as its chloride or nitrate, preferably a nitrate. According to the following XPS data, the lanthanide metals are in the form of oxides in the material; since the detection system is an aqueous solution, the oxide structure is more stable.

[0030] In one embodiment of the present invention, the molar ratio of cyclodextrin to lanthanide salt is 1:8-15, preferably 1:8-12, particularly preferably 1:9-11, for example 1:10. Without being bound by any theory, the inventors have found that the particle size of the final material affects the detection effect. When the amount of cyclodextrin is higher than this ratio, the fluorescence intensity of the material for the same concentration of target substance is higher, but the material structure is very disordered and lacks a specific structure; when the amount of cyclodextrin is lower than this ratio, the fluorescence intensity is insufficient, and the material structure is non-uniform. In this invention, the Z-average particle size of the final material is preferably in the range of 200-250 nm, determined by dynamic light scattering. In this invention, the Z-average particle size of powdered SiO2 is preferably in the range of 180-240 nm, determined by dynamic light scattering.

[0031] In one embodiment of the present invention, based on the total weight of the photo-induced regenerated rare earth fluorescent microsensor SiO2@CD-Ln@Ag2O, the amount of Ag2O is 1.5-5.0 wt%, preferably 2.0-4.0 wt%, and particularly preferably 2.5-3.5 wt%. In the present invention, the content of silver oxide can be calculated by the change in the mass of the materials before and after synthesis.

[0032] In this invention, the Z-average particle size of silver oxide (Ag2O) is 4-10 nm, as determined by dynamic light scattering.

[0033] In one embodiment of the invention, the mass ratio of cyclodextrin to powdered SiO2 is 1:5-10, preferably 1:6-8, particularly preferably 1:7-8, for example 1:7.5. Without being limited to any theory, the inventors have found that by using a mass ratio of cyclodextrin to powdered SiO2 within this range, combined with the aforementioned molar ratio of cyclodextrin to lanthanide metal salts and the loading of Ag2O, a desired Z-average particle size of the final material in the range of 200-250 nanometers can be obtained.

[0034] In this invention, silver nitrate is preferably used as a silver nitrate solution with a concentration of 0.1-0.5 mol / L. -1 .

[0035] The present invention also provides the use of the aforementioned photo-induced regenerated rare earth fluorescent microsensor for detecting tetracycline antibiotic residues in the environment, food, and traditional Chinese medicine.

[0036] In one embodiment of the present invention, the tetracycline antibiotic is an antibiotic containing a tetraphenyl nucleus, preferably chlortetracycline, oxytetracycline, tetracycline, tetracycline hydrochloride, chlortetracycline hydrochloride, methacycline, doxycycline, or dimethylaminotetracycline.

[0037] In one embodiment of the present invention, the photoinduced regenerated rare earth fluorescent microsensor uses 0.2-1.0 mg / mL -1 It is used in the form of an aqueous dispersion.

[0038] The photo-induced regenerated rare earth fluorescent microsensor of the present invention has a novel structure, high sensitivity, and regenerability. It is a material with specific fluorescence sensing for tetracycline antibiotics and can be used for the efficient detection of tetracycline antibiotics. It can be applied to the real-time monitoring of antibiotics in complex matrices such as environment, food, and traditional Chinese medicine.

[0039] Unless otherwise stated, this invention is carried out at room temperature and pressure.

[0040] Unless otherwise stated, the proportions of raw materials in this invention are by mass, and the percentages used are by mass.

[0041] Unless otherwise stated, the modifier "about" before the numerical value in this invention indicates a range of ±1-15, preferably ±1-13, more preferably ±1-10, and even more preferably ±1-5. For example, a material particle size of about 200 nm can be expressed as 200 nm ±15, 200 nm ±13, 200 nm ±10, 200 nm ±5, 200 nm ±3, etc.

[0042] Unless otherwise stated, the raw materials and equipment of this invention are commercially available.

[0043] Example

[0044] Synthesis of Photo-Regenerated Rare Earth Fluorescent Microsensor Materials

[0045] Materials and reagents

[0046] 95% ethanol (AR, 95%, Tianjin Zhiyuan Chemical Reagent Co., Ltd.), anhydrous ethanol (AR, Tianjin Zhiyuan Chemical Reagent Co., Ltd.), sodium chloroacetate (AR, 98%, Shanghai Ron Chemical Technology Co., Ltd.), β-cyclodextrin (98%, Shanghai Ron Chemical Technology Co., Ltd.), silver nitrate (99.8%, Tianjin Aubokai Chemical Co., Ltd.), europium nitrate hexahydrate (99%, Saen Chemical Technology (Shanghai) Co., Ltd.), hydrochloric acid (GR, Sichuan Xilong Science Co., Ltd.), tetracycline (TC, CP, Maclean's), tetracycline hydrochloride Medicinal compounds (TCH, Biotechnology Grade, Maclean's), Oxytetracycline (OTC, 98%, Aladdin), Chlortetracycline Hydrochloride (CTCH, Biotechnology Grade, Maclean's), Chloramphenicol (CP, 98%, Shanghai Ron Chemical Technology Co., Ltd.), Metronidazole (MNZ, 99%, Shanghai Ron Chemical Technology Co., Ltd.), Ofloxacin (OXC, 98%, Shanghai Ron Chemical Technology Co., Ltd.), Ciprofloxacin (CXC, 98%, Shanghai Ron Chemical Technology Co., Ltd.), Sodium Bicarbonate (AR, Tianjin Beilian Fine Chemicals Development Co., Ltd.), Fe 3+ Cu 2+ Zn 2+ Ba 2+ Se 4+ Pb 2+ Cr 3+ and Sb 3+ Standard ionic liquid (Shandong Zhongke Ruipu Technology Co., Ltd.), histidine (His) (99%, Maclean), cysteine ​​(Cys) (99%, Maclean), lysine (Lys) (98%, Maclean), aspartic acid (Asp) (98%, Maclean), dried leeches and earthworms (Xinjiang Baicaotang Pharmaceutical Chain Co., Ltd.).

[0047] Equipment and conditions

[0048] The synthesized carboxylic acid cyclodextrin was analyzed using a nuclear magnetic resonance spectrometer (Quantum-IPlus 600MHz, Zhongke Oxford, China). 1 HNMR and 13CNMR characterization was performed using D2O as the solvent. Field emission scanning electron microscopy (SEM, 100 kV, Fisher Scientific Apreo2C, Thermo Fisher Scientific, America) was used to characterize the morphology of the example sample SiO2@[β-CDCH2COOEu]O@Ag2O (abbreviated as SiO2@β-CD-Eu@Ag2O). High-resolution transmission electron microscopy (HRTEM, Fisher Scientific Talos F200S, Thermo Fisher Scientific, America) combined with energy-dispersive X-ray spectroscopy (EDX) was used to characterize the surface structure, elemental composition, and distribution of SiO2@β-CD-Eu@Ag2O, as well as the TEM characterization of SiO2@[β-CDCH2COOEu]O (abbreviated as SiO2@β-CD-Eu). The crystal phase structure and physical phases of the sample SiO2@β-CD-Eu@Ag2O were characterized by powder X-ray diffraction (XRD, Cutarget, Rigaku Ultima IV, Japan), with a 2θ range from 5° to 85° and a scan rate of 2 min. -1 X-ray photoelectron spectroscopy (XPS, aluminumtarget, Kratos AXISSUPRA+, Shimadzu, Japan) was used to determine the binding energies of elements on the SiO2@β-CD-Eu@Ag2O surface. Fourier transform infrared spectroscopy (FTIR, Thermo Fisher Nicolet Is5, America) was used to measure the binding energies of β-CD-CH2COOH, SiO2@Eu2O3, SiO2@β-CD-Eu, and SiO2@β-CD-Eu@Ag2O samples in the range of 400–4000 cm⁻¹. -1 Infrared shift within the range. A confocal Raman spectrometer (LabRAMHR eVolution, Horiba, Japan) was used with a 532 nm excitation wavelength to measure the infrared shift of the SiO2 sample within the 400-4000 cm⁻¹ range. -1 Raman spectral characterization of SiO2@Eu2O3, SiO2@β-CD-Eu, and SiO2@β-CD-Eu@Ag2O within the specified range. Determination of antibiotic TC(λ) by UV-Vis spectroscopy (UV-2450, Shimadzu, Japan). max =267nm), TCH(λ) max =267nm), CTCH(λ) max =267nm) and OTC(λ) max=268nm). The fluorescence signal was measured using a fluorometer (FL, Hitachi F4500, Japan) (Ex = 396nm).

[0049] 1. A specific photo-induced regenerated rare-earth fluorescent microsensor material of the present invention.

[0050] Synthesis of SiO2@β-CD-Eu@Ag2O

[0051] 1.1 Hydrothermal Synthesis of Carboxylic Acid β-Cyclodextrin

[0052] 10 g of NaOH was dissolved in 30 mL of ultrapure water, followed by the addition of 4.2 g of β-CD, and the mixture was stirred at 90 °C for 1 h. Then, 7 g of sodium chloroacetate powder was added, and the mixture was stirred for another 24 h while maintaining the temperature. After the reaction solution cooled to room temperature, 16 mL of concentrated HCl was added to adjust the pH to 4. The solution was then cooled to room temperature, and 60 mL of a 1:3 (v / v) mixture of methanol and ethanol was added, followed by rapid stirring. After complete precipitation, the white precipitate was collected by vacuum filtration, washed successively with methanol and anhydrous ethanol, and dried under vacuum at 40 °C for 3 h to obtain 3.8 g of white powdered β-cyclodextrin acetate (β-CD-CH2COOH·2C2H5OH), with a yield of 90%.

[0053] 1 H-NMR (D2O, 600MHz) δ: 5.70 (1H, s, COOH), 5.51 (7H, br s, H1), 4.35 (13H, m, H3+H7+CH3CH2OH), 4.28 (21H, br s, H5+H6), 4.09 (7H, d, J=6Hz, H2), 4.03 (7H, t, J=12Hz, H4), 1.56 (3H, t, J=6Hz, CH3CH2OH).

[0054] 13 C-NMR (D2O, 600MHz) δ: 176.0 (C-8), 103.9 (C-1), 76.0 (C-7), 72.9 (C-5), 72.4 (C-3), 69.0(C-4), 67.1(C-2), 62.8(C-6), 58.1(CH3CH2OH), 17.8(CH3CH2OH).

[0055] 1.2 Synthesis of SiO2@β-CD-Eu

[0056] Weigh out 0.2 g of β-cyclodextrin carboxylic acid and 0.8 g (1.8 mmol) of europium nitrate hexahydrate.

[0057] (Eu(NO3)3·6H2O), dissolved in 20 mL of ultrapure water. Sonicated at room temperature for 30 min, then at 500 rpm. -1 The mixture was stirred for 2 hours to ensure adequate coordination. Then, 1.5 g of powdered SiO2 (with a Z-average particle size of approximately 210 nm, determined by dynamic light scattering) was added gradually in batches to the above mixed solution, and the mixture was ground until dry. The resulting solid was transferred to an oven and heated at 115 °C for 6 hours. The product was washed with 150 mL of ultrapure water to remove impurities, then washed with anhydrous ethanol, and dried under vacuum at 40 °C for 3 hours to obtain white powdered SiO2@β-CD-Eu.

[0058] 1.3 Synthesis of SiO2@β-CD-Eu@Ag2O

[0059] Disperse 1.8 g SiO2@β-CD-Eu in 10 mL of ultrapure water, and slowly add 15 mL of 0.1 mol / L solution. -1 silver nitrate solution, and at 300 rpm -1 Stir for 1 hour. Then, filter the suspension and wash the filter with 95% ethanol and anhydrous ethanol in sequence. Finally, transfer it to an oven at 115°C and heat for 6 hours to obtain a grayish-white powder SiO2@β-CD-Eu@Ag2O (Amount of Ag2O is 2.8 wt%, based on the weight of SiO2@β-CD-Eu@Ag2O).

[0060] 2. Preparation of the comparative material SiO2@Eu2O3

[0061] The SiO2@Eu2O3 material was synthesized using the same method as in 1.2, except that β-cyclodextrin was not added during the synthesis process.

[0062] Fluorescence performance evaluation

[0063] The following experiments were conducted to determine the effectiveness of the obtained material of the present invention. Each experiment was repeated three times, and the average value was taken. The experimental results are shown in [reference needed]. Figure 1-5 And subsequent explanations.

[0064] 1. Fluorescence response of the synthesized material to tetracycline (TC)

[0065] The fluorescence responses of the materials SiO2@Eu2O3, SiO2@β-CD-Eu and SiO2@β-CD-Eu@Ag2O to tetracycline were compared.

[0066] Each material was prepared to a concentration of 0.5 mg / L. -1 The aqueous dispersions were sonicated for 10 min, and 3 mL of each dispersion was taken and 30 μL of 1 g L solution was added to each. -1The fluorescence intensity of the tetracycline ethanol solution was measured after sonication for 10 minutes. Simultaneously, it was compared with the dispersion of the material without added TC.

[0067] 2. Fluorescence response time of SiO2@β-CD-Eu@Ag2O to TC

[0068] The concentration was prepared as 0.5 mg / mL. -1 SiO2@β-CD-Eu@Ag2O aqueous dispersion, take 3 mL of aqueous dispersion and add 30 μL of 1 g L -1 The tetracycline ethanol solution was subjected to agitation and sonication, and the fluorescence intensity of the mixture was measured every 1 minute for a total duration of 10 minutes.

[0069] 3. Effect of pH on the fluorescence response of SiO2@β-CD-Eu@Ag2O bound to TC

[0070] An acidic buffer solution with pH 4-6 was prepared using acetic acid / sodium acetate; an alkaline buffer solution with pH 8-10 was prepared using sodium carbonate / sodium bicarbonate. A 0.5 mg / mL solution was prepared using these buffer solutions. -1 Take 3 mL of each of the SiO2@β-CD-Eu@Ag2O dispersions and add them to 30 μL of a 1 g L⁻¹ concentration. -1 The fluorescence intensity of the mixture was measured after sonicating a tetracycline ethanol solution for 10 minutes.

[0071] 4. Effect of the amount of SiO2@β-CD-Eu@Ag2O on the fluorescence response of bound TC.

[0072] Prepare 0.2 mg mL of each. -1 0.5 mg mL -1 and 1 mg mL -1 Take 3 mL of SiO2@β-CD-Eu dispersion and add 15, 30, and 60 μL of 1×10⁻⁶ concentration respectively. -4 1×10 -3 1×10 -2 1×10 -1 and 1g L -1 A tetracycline ethanol solution was sonicated for 10 min, and the fluorescence intensity of the mixture was measured. The effects of different material dosages and tetracycline concentrations (0.5–4 × 10⁻⁶) on the results were investigated. 4 ng mL -1 Fluorescence response within the range (F) 617 / F 592 Simultaneously, 0.5 mg mL was selected. -1 The effects of tetracycline concentrations in SiO2@β-CD-Eu@Ag2O aqueous dispersions on the study of tetracycline concentrations in the range of 0.5-4×10⁻⁶. 4 ng mL-1 Fluorescence response within the range (F) 617 / F 592 ).

[0073] 5. Effects of different interfering substances on the fluorescence response of SiO2@β-CD-Eu@Ag2O bound to TC

[0074] The prepared concentrations were 0.01 g / L. -1 Fe 3+ Cu 2+ Zn 2+ Ba 2+ Se 4+ Pb 2+ Cr 3+ Sb 3+ Cl - A solution of glucose, histidine, cysteine, lysine, and aspartic acid was prepared. 0.5 mg mL solutions were then prepared using these solutions. -1 Take 3 mL of each SiO2@β-CD-Eu@Ag2O dispersion and add 30 μL of a 1 g L⁻¹ solution. -1 The fluorescence intensity of the mixture was measured after sonicating a tetracycline ethanol solution for 10 minutes.

[0075] 6. Fluorescence response of SiO2@β-CD-Eu@Ag2O material to various antibiotics

[0076] Prepare concentrations of 1×10 -4 1×10 -3 1×10 -2 1×10 -1 and 1g L -1 Solutions of tetracycline hydrochloride, oxytetracycline, chlortetracycline hydrochloride, chloramphenicol, metronidazole, ciprofloxacin, and ofloxacin were prepared. Based on the differences in the solubility of various antibiotics, tetracycline hydrochloride and chlortetracycline hydrochloride were prepared with ultrapure water, chloramphenicol with 95% ethanol, and oxytetracycline, metronidazole, ciprofloxacin, and ofloxacin with 0.01 mol / L solutions. -1 Preparation of hydrochloric acid solution. Add 0.5 mg / mL of the solution to each solution. -1 Different volumes (15, 30, and 60 μL) of antibiotic solution were added to SiO2@β-CD-Eu@Ag2O aqueous dispersions. After sonication for 10 min, the fluorescence intensity of the mixture was measured. The material was analyzed in the range of antibiotic concentrations from 0.001 to 40 μg / mL. -1 Fluorescence response range (F) 617 / F 592 ).

[0077] 7. Spiking experiment on real samples

[0078] Dried samples of leeches and earthworms were pulverized and passed through a No. 3 sieve. 10g of each sample was weighed and extracted with 200mL of ultrapure water using ultrasonic extraction for 30min. The mixture was then centrifuged, and the supernatant was collected. After filtration through a 0.22μm filter membrane, the supernatant was transferred to a volumetric flask and diluted to 250mL with water (original solution). The original solution was tested for the presence of tetracycline antibiotics using a UV spectrophotometer. Then, 0.01g L / L solutions were prepared using the original solutions of both samples. -1 and 0.1g L -1 Tetracycline, tetracycline hydrochloride, oxytetracycline, and chlortetracycline hydrochloride solutions (spike solutions). Take 3 mL of the material's aqueous dispersion and add it to the above spike solutions respectively to make the antibiotic concentration reach 0.2 μg / mL. -1 0.5 μg mL -1 1.0 μg mL -1 The spiking levels were determined, and the fluorescence response of SiO2@β-CD-Eu@Ag2O to different antibiotics was measured to evaluate its detection capability in complex matrices.

[0079] Degradability and Renewability of Sensing Materials

[0080] 1. Degradation performance of SiO2@β-CD-Eu@Ag2O on TC

[0081] The concentration was prepared as 0.5 mg / mL. -1 Take 3 mL of the SiO2@β-CD-Eu@Ag2O aqueous dispersion and add 60 μL of 0.1 g L⁻¹ solution. -1 Tetracycline solution, after being sonicated for 10 min to achieve uniform dispersion, was placed in darkness, under an LED light (455nm, 50W), and under outdoor sunlight (1.1×10⁻⁶ W). 5 The concentration of TC was measured after 30, 60, 90, 120, 150 and 180 min under LX (20℃) illumination.

[0082] 2. Degradation cycle performance of SiO2@β-CD-Eu@Ag2O on TC under visible light

[0083] Prepare 0.5 mg mL -1 Take 3 mL of the SiO2@β-CD-Eu@Ag2O aqueous dispersion and add 60 μL of a 0.1 g L⁻¹ solution. -1 The tetracycline solution was sonicated for 10 min and then placed under an LED lamp (455 nm, 50 W) for 180 min. After the reaction, the TC concentration of the filtrate was measured using a UV-Vis spectrophotometer. Simultaneously, the material after light exposure was recovered, washed sequentially with pure water and anhydrous ethanol, vacuum dried at 40 °C for 1 h, and then heated in an oven at 115 °C for 6 h for reuse in degradation experiments. The above material was recycled four times to evaluate its reusability.

[0084] 3. Degradation performance of SiO2@β-CD-Eu@Ag2O on different antibiotics under visible light.

[0085] Prepare 0.5 mg mL -1 Take 3 mL of the SiO2@β-CD-Eu@Ag2O aqueous dispersion and add 60 μL of 0.1 g L⁻¹ solution. -1 Solutions of tetracycline hydrochloride, oxytetracycline, and chlortetracycline hydrochloride were uniformly dispersed by sonication for 10 minutes and then placed under an LED lamp (455nm, 50W) and outdoor sunlight (1.1×10⁻⁶ W), respectively. 5 After LX (at 20℃) for 180 min, the concentrations of each antibiotic were measured, and the degradation rate was calculated using equation (1):

[0086] η(%)=(1-C t / C0)×100% (1)

[0087] In the formula, η is the degradation rate, and C0 is the initial concentration of the target substance (mg / mL). -1 ), C t The concentration at time t (mg / mL) -1 ).

[0088] 4. Renewable investigation of the fluorescence properties of SiO2@β-CD-Eu@Ag2O material

[0089] Prepare 0.5 mg mL of the recycled material described in Section 3 above in sequence. -1 The aqueous dispersion was taken in batches of 3 mL, and the tetracycline concentration was determined to be 10⁻¹⁰. 4 ng mL -1 The fluorescence intensity at that time was used to assess the retention of the material's TC detection performance after repeated use.

[0090] Determination and effect of sensor material structure

[0091] The synthesis of SiO2@β-CD-Eu@Ag2O in this invention is as follows: Figure 1 As shown in (a). Figure 1 (b) is the XPS photoelectron spectrum of the material SiO2@β-CD-Eu@Ag2O, which contains characteristic peaks of binding energy for Eu 3d (1165.5 and 1135.6 eV), O 1s (532.9 eV), Ag 3d (373.9 and 367.9 eV), C 1s (286.0 eV), Si 2s (155.5 eV) and Si 2p (104.6 eV). Figure 1 In (c), Ag 3d shows two binding energy sites at 373.9 and 367.9 eV, which can be attributed to the characteristic peaks of Ag 3d5 / 2 and Ag 3d3 / 2 of Ag2O, respectively. Figure 1 In (d), Eu 3d corresponds to the characteristic peaks of Eu 3d5 / 2 and Eu 3d3 / 2 of Eu2O3 at 1165.5 eV and 1135.6 eV, respectively; Figure 1 The fine spectrum of C1s in (e) can be divided into four binding energy sites: 293.0, 290.4, 286.6, and 284.8 eV. The peak at 293.0 eV is attributed to CO2 adsorbed on the material surface, while the peaks at 290.4 eV, 286.6, and 284.8 eV are attributed to C=O, CO, and CC, respectively. Referring to the standard binding energy values ​​of Eu2O3 (Eu 3d5 / 2: 1165.1 eV; Eu 3d3 / 2: 1135.3 eV), the Eu 3d5 / 2 and Eu 3d3 / 2 binding energies of Eu2O3 increase by 0.4 eV and 0.3 eV, respectively, indicating electron migration into their empty orbitals. Compared to the standard binding energy of the carboxylic acid group (C=O) (289.4 eV), the C1s binding energy of the carbonyl group in the material increases by 1.0 eV, indicating that the O in the carboxylic acid... - Electrons of ions migrate into Eu 3+ The change in binding energy indicates that a coordination reaction occurred between Eu2O3 and the carboxylic acid group of the modified cyclodextrin in the empty orbitals.

[0092] Figure 1 (f) shows the XRD analysis results of the material SiO2@β-CD-Eu@Ag2O. A broad peak with 2θ values ​​observed between 20.0° and 30.0° is attributed to amorphous SiO2. A diffraction peak was detected at 2θ = 38.2°, which matches the Ag2O(111) crystal plane (JCPDS 41-1104 standard card), indicating the presence of Ag2O in the sample. Furthermore, no diffraction peaks of Eu2O3 were observed in the XRD pattern, suggesting that Eu2O3 is mainly uniformly dispersed in an amorphous structure in this system.

[0093] Figure 1 (gk) shows the SEM and TEM images of SiO2@β-CD-Eu@Ag2O, and the TEM image of SiO2@β-CD-Eu. SEM results ( Figure 1 (g) indicates that the SiO2@β-CD-Eu@Ag2O microspheres are uniform in size, with an average diameter of about 223 nm, and the surface is uniformly distributed with obvious nanoparticles, with no scattered particles or fragments around them.

[0094] With SiO2@β-CD-Eu( Figure 1 Compared to the TEM image of (h), SiO2@β-CD-Eu@Ag2O( Figure 1 (i) Uniformly attached 5-10 nm crystal particles on the surface. Further EDS elemental mapping analysis was performed on random individual spheres ( Figure 1(j) shows the uniform distribution and content of each element on the microspheres (Si > Eu > C > Ag), with Ag being well dispersed and having a low content. This result is consistent with the absence of a strong Ag₂O diffraction peak detected by XRD and the weak Ag 3d peak in XPS, confirming the low content of Ag₂O in the SiO₂@β-CD-Eu@Ag₂O composite material. HRTEM analysis ( Figure 1 (k) further revealed the crystal structure of the material SiO2@β-CD-Eu@Ag2O, and the measured and The lattice spacings correspond to the Ag₂O (111) and (200) crystal planes, respectively, matching the JCPDS 41-1104 standard card. On the other hand, no Eu₂O₃-related lattice fringes were detected, consistent with the absence of Eu₂O₃ diffraction peaks in XRD, indicating that Eu₂O₃ is mainly distributed in an amorphous state on the microsphere surface. These results demonstrate that Eu₂O₃, β-CD, and Ag₂O have been successfully located on the SiO₂ microsphere surface and exist in a uniformly dispersed state.

[0095] Figure 2 (a) shows the FTIR spectra of materials β-CD-CH2COOH, SiO2@Eu2O3, SiO2@β-CD-Eu and SiO2@β-CD-Eu@Ag2O; Figure 2 (b) Raman spectra of SiO2@Eu2O3 and its composite materials are shown. In the FTIR spectrum of β-CD-CH2COOH, the value is 1602 cm⁻¹. -1 The peak at 1418 cm⁻¹ is attributed to the C=O stretching vibration, further indicating that β-CD-CH₂COOH has been successfully synthesized. Additionally, the peak at 1418 cm⁻¹... -1 and 1329cm -1 Characteristic peaks at 1634 cm⁻¹ can be attributed to CC and CH, respectively. (SiO₂@Eu₂O₃ at 1634 cm⁻¹) -1 The peak at 1469 cm⁻¹ is attributed to the bending vibration of Eu-OH, while the peak at 1469 cm⁻¹ is attributed to the bending vibration of Eu-OH. -1 and 1384cm -1 The peaks are attributed to Eu-O stretching and bending vibrations, respectively. However, in the spectra of SiO2@β-CD-Eu and SiO2@β-CD-Eu@Ag2O, these characteristic peaks change significantly, with the 1634 cm⁻¹ peak showing a more pronounced change. -1 The intensity of the vibration peak decreased, while the 1469cm peak... -1 and 1384cm -1 The Eu-O vibration peak at the location completely disappeared, indicating that Eu 3+ It coordinated with the carboxyl group of β-CD-CH2COOH. Raman spectroscopy further confirmed this conclusion. Figure 2As shown in (b), at an excitation wavelength of 532 nm, SiO2@Eu2O3 exhibits high performance at 1554, 1910, 2540, and 2597 cm⁻¹. -1 The characteristic peak at 1554 cm⁻¹ can be attributed to the Eu-O vibrational mode. In contrast, the spectra of SiO₂@β-CD-Eu and SiO₂@β-CD-Eu@Ag₂O show significant changes, with the peak at 1554 cm⁻¹ being particularly prominent. -1 Redshifted to 1505cm -1 2540cm -1 and 2597cm -1 Redshifted to 2454cm -1 and 2568cm -1 And form a peak, at 1779 cm⁻¹ -1 New peaks appeared at this point. These peak position changes further indicate that Eu... 3+ Coordination affects the Eu-O bond length and its electron cloud distribution, leading to changes in peak position. Furthermore, XPS analysis shows an increase in the Eu 3d binding energy in SiO2@β-CD-Eu@Ag2O, indicating that Eu... 3+ The increased electron density further confirms Eu 3+ The interaction with the carboxyl group. The XPS, FTIR, and Raman results above collectively confirm that Eu... 3+ Through coordination, it forms a stable complex with β-CD-CH2COOH, significantly affecting the vibrational modes of Eu-O and C=O.

[0096] The results of the fluorescence response study of the synthesized material to tetracycline (TC) are as follows: Figure 3 As shown in (a), none of the three materials, SiO2@Eu2O3, SiO2@β-CD-Eu, and SiO2@β-CD-Eu@Ag2O, showed obvious fluorescence peaks before the addition of tetracycline. However, after the addition of TC, they all showed emission peaks at 579, 592, and 617 nm, respectively, corresponding to Eu2O3, Eu2O3, and β-CD-Eu, respectively. 3+ of 5 D0- 7 F0、 5 D0- 7 F1 and 5 D0- 7 The F2 transition occurs. The maximum emission peak is at 617 nm. Comparison shows that SiO2@β-CD-Eu exhibits the highest fluorescence intensity (728.5 au), which is 1.8 times that of SiO2@β-CD-Eu@Ag2O (394.8 au) and 4.8 times that of SiO2@Eu2O3 (151.8 au), respectively. This indicates that SiO2@β-CD-Eu and SiO2@β-CD-Eu@Ag2O can serve as good fluorescent probes for TC detection. The kinetic adsorption results of TC by SiO2@β-CD-Eu@Ag2O are as follows... Figure 3 As shown in (b), the fluorescence intensity of the SiO2@β-CD-Eu@Ag2O colloidal aqueous solution gradually increases with increasing sonication time, reaching equilibrium after approximately 8 minutes. To obtain optimal sensitivity, fluorescence was detected after 10 minutes of sonication.

[0097] The results of the investigation on the effect of pH on the fluorescence response of SiO2@β-CD-Eu@Ag2O bound to TC are as follows: Figure 3 As shown in (c), SiO2@β-CD-Eu@Ag2O exhibits a good fluorescence intensity response to tetracycline within the pH range of 7-10. However, within the pH range of 4-6, a significant decrease or even quenching of the fluorescence intensity of the mixture is observed. This may be attributed to the fact that in an acidic environment, the tetracycline molecule is fully protonated, which is unfavorable for its interaction with Eu. 3+ Coordination occurs. When pH > 8, the decrease in fluorescence intensity of the material to TC may be due to the formation of Eu(OH)3 precipitate under alkaline conditions.

[0098] To further evaluate the performance of the composite material in tetracycline fluorescence sensing, the effects of different SiO2@β-CD-Eu dosages (0.2, 0.5, and 1.0 mg / mL) were investigated. -1 ) and TC concentration (0.5-4×10 4 ng mL -1 The fluorescence response relationship between the three material dosages was investigated to determine the appropriate dosage of the composite material. Experimental results showed that the fluorescence intensity increased with increasing tetracycline concentration at all three material dosages, and the ratio of fluorescence response (F...)... 617 / F 592 The relationship between ) and TC concentration showed a good linear relationship. Figure 3 (d)-(f)). When the amount of material used is 0.2 mg / mL -1 hour( Figure 3 (d)), the tetracycline concentration was 10⁻¹×10⁻¹ 3 ng mL -1 Within the range, its linear regression equation is F 617 / F 592 =

[0099] 0.0015[C]+1.5421(R 2 =0.9962), the limit of detection (LOD) and the limit of quantitation (LOQ) were 6 ng / mL. -1 and 21ng mL -1 When the material dosage is 0.5 mg / mL -1 hour( Figure 3 (e)), the tetracycline concentration is 0.5-2×10 3 ng mL -1 Within the range, the linear regression equation is F617 / F 592 =0.0014[C]+1.2115(R) 2 =0.9921), LOD and LOQ were 0.6 ng / mL. -1 and 2ng mL -1 When the material dosage is 1.0 mg / mL -1 hour( Figure 3 (f)), F 617 / F 592 The value is related to the tetracycline concentration in the range of 5-2×10. 3 ngmL -1 The linear relationship is observed within the range, and its linear regression equation is F. 617 / F 592 =0.0031[C]+1.1518(R) 2 =0.9908), LOD and LOQ are 2ng / mL. -1 and 5ng mL -1 The results showed that when the material concentration was 0.5 mg / mL -1 At this point, it exhibits the lowest limit of detection and the widest linear range. Therefore, 0.5 mg / mL was selected. -1 The relationship between tetracycline concentration and fluorescence response was investigated in SiO2@β-CD-Eu@Ag2O materials. The results are as follows: Figure 3 As shown in (g), when the TC concentration is 10⁻¹×10⁻¹ 4 ng mL -1 Within the range of F 617 / F 592 The values ​​exhibit a linear relationship, and its linear regression equation is F. 617 / F 592 =0.0014[C]+1.2115(R) 2 =0.9921), LOD and LOQ were 6 ng / mL. -1 and 21ng mL -1 Compared with the material SiO2@β-CD-Eu, the detection limit of SiO2@β-CD-Eu@Ag2O is lower, and its detection range is expanded.

[0100] The inventors discovered that when the material concentration is below 0.2 mg / mL -1 The limited number of fluorescent sites leads to a lower probability of interaction with target molecules, resulting in a relatively weak fluorescence response signal. This, in turn, reduces the signal-to-noise ratio of the detection system, increasing the limit of detection (LOD). Although the detection range is relatively wide, the sensitivity is insufficient. When the material concentration is increased to a moderate level (e.g., 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9 mg / mL), the sensitivity decreases. -1At this concentration, the binding ratio between the fluorescent site and the target molecule is more reasonable, effectively avoiding the problems of saturation or excess of reaction sites, thus achieving optimal fluorescence enhancement and response linearity. At this concentration, the "antenna effect" of the Eu-based fluorescent probe is fully utilized, making the fluorescence intensity more sensitive to changes in tetracycline concentration, resulting in a significantly lower detection limit and the widest linear range, exhibiting the best detection performance. However, further increasing the material dosage to 1.0 mg / mL... -1 At concentrations above this level, the probability of material aggregation increases significantly, potentially inducing internal filtration and fluorescence self-quenching, thus inhibiting the effective release of the fluorescence signal. Simultaneously, excessive fluorescent sites dilute the excitation effect of the target molecule on specific sites, causing the fluorescence response signal to tend towards saturation, resulting in a narrowing of the linear range and a rise in the detection limit. Therefore, the concentration of fluorescent material plays a crucial role in regulating the performance of fluorescent probes, requiring an optimal balance between enhancing the response signal and suppressing background interference, ideally between 0.2-1.0 mg / mL. -1 The optimal dosage significantly improves detection accuracy and linearity while ensuring response sensitivity.

[0101] In practical measurements, the influence of various interfering substances, such as metal ions, inorganic salts, amino acids, and sugars, usually needs to be considered. To assess potential interfering factors, the following investigations are conducted.

[0102] The fluorescence response of SiO2@β-CD-Eu@Ag2O under different interfering conditions is as follows: Figure 3 As shown in (h). In Zn 2+ Ba 2+ Se 4+ Pb 2+ Cr 3+ Sb 3+ In the presence of glucose and amino acids (His, Lys, Asp), the fluorescence intensity of the material did not change significantly, indicating that the SiO2@β-CD-Eu@Ag2O material has good anti-interference ability against the above-mentioned interfering substances. However, in the presence of Fe... 3+ Cu 2+ Cl - The fluorescence intensity decreases in the presence of Cys. This is because Fe is present in Cys. 3+ and Cu 2+ It may form complexes with tetracycline and materials, leading to fluorescence quenching; the thiol group (-SH) in Cys reacts with Cl... - Both can be used with Ag + The reaction occurs, disrupting the material structure. It is evident that the SiO2@β-CD-Eu@Ag2O material maintains a good fluorescence signal even in the presence of most interfering substances, demonstrating its excellent anti-interference ability.

[0103] The fluorescence response of the material to eight antibiotics, including tetracyclines (TC, TCH, OTC, and CTCH), quinolones (OXC and CXC), CP, and MNZ, was investigated. The results are as follows: Figure 3 As shown in (i), the material SiO2@β-CD-Eu@Ag2O exhibits fluorescence responses to tetracycline hydrochloride, chlortetracycline, oxytetracycline hydrochloride, ciprofloxacin, and ofloxacin. Specifically, tetracycline antibiotics show pink fluorescence; ciprofloxacin and ofloxacin show green fluorescence; chloramphenicol (CP) and metronidazole (MNZ) show no fluorescence response. A significant linear relationship exists between the concentrations of tetracycline hydrochloride, chlortetracycline, and oxytetracycline hydrochloride and the fluorescence response of the material. Figure 3 The linear equation for tetracycline hydrochloride shown in (j) is F 617 / F 592 =0.0011[C]+1.0848(R) 2 =0.9933; 20-5×10 3 ng mL -1 LOD: 15 ng / mL -1 LOQ: 50 ng / mL -1 ). Figure 3 The linear equation for chlortetracycline hydrochloride shown in (k) is F 617 / F 592 =0.0002[C]+1.1219(R) 2 =0.9940; 50-7×10 3 ng mL -1 LOD: 45 ng / mL -1 LOQ: 148 ng / mL -1 ). Figure 3 The linear equation for oxytetracycline shown in (l) is F 617 / F 592 =0.0006[C]+0.8811(R) 2 =0.9921; 20-2×10 3 ngmL -1 LOD: 10 ng / mL -1 LOQ: 33ng / mL -1 These results indicate that SiO2@β-CD-Eu@Ag2O exhibits a specific fluorescent response to tetracycline antibiotics and demonstrates strong selectivity.

[0104] To evaluate the detection capability of SiO2@β-CD-Eu@Ag2O for tetracycline antibiotics in real samples, spiked recovery experiments were conducted using earthworm and leech extracts. The results are shown in Table 1. Tetracycline, tetracycline hydrochloride, oxytetracycline, and chlortetracycline hydrochloride were not detected in the aqueous extracts of either sample. Recovery was achieved at three spiking levels (0.2, 0.5, and 1.0 μg / mL) in both real samples. -1 Under these conditions, the recoveries of the four antibiotics ranged from 83.9% to 109.5%, with relative standard deviations (RSDs) all below 4.7%. This result indicates that the material SiO2@β-CD-Eu@Ag2O can be directly applied to the detection of tetracycline antibiotics in real samples without complex pretreatment steps.

[0105] In the spiked recovery experiment, the recovery rate met the requirements of the national standard GB-T27404. Some sample groups showed recoveries exceeding 100%, which may be caused by the following factors: First, trace amounts of background tetracycline may exist in the sample matrix. If the background value is not sufficiently subtracted, the measurement result will be too high (TCs were not detected in the sample). Second, in the fluorescence ratio method, the energy transfer of coexisting substances to the characteristic emission peak or weak fluorescence interference may produce positive signal enhancement, thereby amplifying the ratio response. Furthermore, when the spiked concentration is near the method detection limit or close to the linear range boundary, signal fitting error may also lead to quantitative deviation. A recovery rate slightly higher than 100% is within an acceptable range and still indicates that the detection method is well-suited for practical samples.

[0106] Table 1: Results of tetracycline antibiotic spiking experiments in earthworm and leech samples

[0107]

[0108] like Figure 4 As shown in (a), the photodegradation of TC under four conditions were investigated: "Blank" (LED, TC), "Adsorption" (darkness, TC + material), "Sun" (outdoor sunlight, TC + material), and "LED" (LED, TC + material). Under the "Blank" condition, 2 mg L... -1 Tetracycline solution showed only a 4.2% degradation rate within 180 minutes under LED irradiation. Under "Adsorption" conditions, SiO2@β-CD-Eu@Ag2O adsorbed approximately 60.3% of the tetracycline within 180 minutes. Under "Sun" conditions, the material achieved a 92.7% photodegradation rate for tetracycline. Under "LED" conditions, the photodegradation rate reached 96.7%. These results demonstrate that SiO2@β-CD-Eu@Ag2O exhibits excellent photodegradation capabilities for tetracycline.

[0109] like Figure 4 As shown in (b), the reusability of SiO2@β-CD-Eu@Ag2O under degradation was investigated. Under LED illumination, after four cycles (180 min each), the degradation efficiencies of tetracycline were 96.7%, 95.4%, 94.9%, and 90.9%, respectively. The results show that the degradation rate in the fourth use decreased by only about 6% compared to the first use, with minimal performance loss. This indicates that the material possesses excellent reusable photodegradation capabilities.

[0110] like Figure 4 As shown in (c), the degradation capabilities of SiO2@β-CD-Eu@Ag2O for tetracycline hydrochloride, chlortetracycline hydrochloride, and oxytetracycline were investigated. SiO2@β-CD-Eu@Ag2O exhibited good degradation capabilities for tetracycline antibiotics of the same concentration under both LED and outdoor sunlight irradiation. Specifically, the degradation rate of tetracycline and tetracycline hydrochloride reached over 96.0% under LED lighting, and the degradation rate for both reached over 84.0% under sunlight irradiation. The degradation of all four tetracyclines was achieved under both laboratory conditions and real outdoor sunlight irradiation. This indicates that SiO2@β-CD-Eu@Ag2O can achieve green degradation of various tetracycline antibiotics.

[0111] like Figure 4 As shown in (d), the results of the fluorescence performance regeneration investigation of the material are presented. First use of the material SiO2@β-CD-Eu@Ag2O: F 617 / F 592 =0.0014[C]+1.2115(R) 2 =0.9921; 10-10 4 ng mL -1 LOD: 6 ng / mL -1 LOQ: 21 ng / mL -1 First reuse: F 617 / F 592 =0.0008[C]+1.7673(R) 2 =0.9963; 100-9×10 3 ng mL -1 LOD: 78 ng / mL -1 LOQ: 257 ng / mL -1 ); Second reuse: F 617 / F 592 =0.0006[C]+1.8938(R) 2 =0.9929; 100-9×10 3 ng mL -1 LOD: 81 ng / mL -1LOQ: 270 ng / mL -1 Third reuse: F 617 / F 592 =0.0006[C]+2.2083(R) 2 =0.9922; 100-8×10 3 ng mL -1 LOD: 87 ng / mL -1 LOQ: 288ng / mL -1 Fourth repetition: F 617 / F 592 =0.0004[C]+2.9155(R) 2 =0.9914; 100-8×10 3 ng mL -1 LOD: 93 ng / mL -1 LOQ: 310 ng / mL -1 After 5 cycles, the LOD of SiO2@β-CD-Eu@Ag2O still reached 93 ng / mL. -1 The linear range remains within 100-8×10 3 ng mL -1 . Figure 4 (d) shows that the slope of the linear equation decreases with increasing usage frequency, which may be due to a small amount of intermediates competing with TC for Eu during photodegradation. 3+ This is due to the coordination sites. The material of this invention maintains high sensitivity for TC detection within 5 cycles, and its limit of detection still meets the EU limit for tetracycline (100 μg / kg). -1 ), indicating the material

[0112] SiO2@β-CD-Eu@Ag2O possesses stable and sustainable utilization capabilities.

[0113] Figure 5 (a) shows the UV-Vis absorption spectra of SiO2@Eu2O3, TC, and SiO2@Eu2O3+TC. No obvious absorption peaks were observed in the wavelength range of 265 to 700 nm for SiO2@Eu2O3. TC exhibited distinct shoulder peaks at 267 nm and 356 nm. After the addition of TC to SiO2@Eu2O3, the shoulder peak of TC shifted from 356 nm to 395 nm, showing a significant redshift. Figure 5 As shown in (b), the fluorescence spectra of SiO2@Eu2O3 before and after the addition of TC are observed. The fluorescence intensity of SiO2@Eu2O3 at 592 and 617 nm is significantly enhanced after the addition of TC. The triplet energy level of TC (18100 cm⁻¹) is also shown. -1 Located in Eu 3+ of5 D0(17260cm -1 )and 5 D1(19020cm -1 Between energy levels, TC is in relation to Eu 3+ After coordination, energy transfer can be achieved through the antenna effect, thereby enhancing Eu. 3+ Fluorescence emission.

[0114] Depend on Figure 3 (a) shows that the fluorescence intensity of SiO2@β-CD-Eu+TC is significantly higher than that of SiO2@Eu2O3+TC. Figure 5 (c) shows the UV absorption spectra of TC and TC+β-CD. It reveals that the UV absorption intensity of TC significantly decreases upon the addition of β-CD to the TC solution, indicating an interaction between the two. β-CD can introduce TC into its hydrophobic cavity through host-guest encapsulation. The strong affinity of the CD cavity for TC promotes TC encapsulation and shortens the time between TC and Eu. 3+ The increased distance significantly enhances the antenna effect. Furthermore, XPS, FTIR, and Raman spectroscopy all indicate that carboxylic acid-modified β-CD can interact with Eu... 3+ Coordination occurs, causing it to be tightly fixed on the surface of SiO2 microspheres. This process effectively reduces the impact of water molecules on Eu. 3+ The fluorescence quenching effect, based on the synergistic effect of the two mechanisms mentioned above, makes the fluorescence intensity of SiO2@β-CD-Eu+TC higher than that of SiO2@Eu2O3+TC.

[0115] like Figure 5 (d) shows the bonding model diagram of Eu₂O₃-TC-Ag₂O. On the surface of silica spheres, Eu… 3+ It coordinates with β-CD-CH2COOH, and after TC inserts into β-CD, it reacts with Eu. 3+ Combined with enhanced fluorescence response.

[0116] Ag2O can be excited and generate free radicals (ROS: ·OH and ·O2) under visible light irradiation. - ).like Figure 5 As shown in (e), SiO2@β-CD-Eu@Ag2O can effectively degrade various tetracycline antibiotics under LED light and outdoor sunlight irradiation, indicating that Ag2O plays a dominant role in the photodegradation process. SiO2@β-CD-Eu@Ag2O fixes TC molecules through adsorption and coordination, and Ag2O generates ROS under visible light excitation, which reacts with TC in a photodegradation reaction. During the photodegradation process, some Ag2O may decompose to produce nano-Ag, which further improves the separation efficiency of photogenerated electrons through the resonance energy transfer effect (SPR), resulting in a high photodegradation efficiency.

[0117] The photo-regenerable fluorescent composite material of this invention effectively improves the fluorescence detection sensitivity of tetracycline compounds through the coordination of Ln metal ions with tetracycline compounds and the host-guest recognition effect of β-CD. Simultaneously, the introduction of Ag₂O nanoparticles provides the material with excellent visible light photocatalytic regeneration capabilities. The photo-regenerable rare-earth fluorescent microsensor material of this invention exhibits an ultra-low detection limit (e.g., 0.6 ng / mL) for tetracycline compounds. -1 ) and wide linear range (e.g., 0.5-2×10) 3 ng mL -1 It exhibits excellent resistance to interference and high recovery rates (e.g., above 83.0%) in complex matrices.

[0118] Furthermore, under visible light irradiation, the material SiO2@β-CD-Eu@Ag2O can degrade more than 96% of tetracycline compounds in 180 min, and still maintains more than 90% degradation activity after 5 cycles of use, while its LOD can still reach 93 ng / mL. -1 This meets the actual needs of sample monitoring.

Claims

1. A coronavirus-like photo-regenerated rare-earth fluorescent microsensor (SiO2@CD-Ln@Ag2O), wherein the photo-regenerated rare-earth fluorescent microsensor comprises SiO2 microspheres, a lanthanide (Ln)-cyclodextrin (CD) coordination layer, and Ag2O nanoparticles; The SiO2 microspheres form the core, and the SiO2 microspheres are coated with a lanthanide metal-cyclodextrin coordination layer. Ag2O nanoparticles are loaded onto this coordination layer.

2. The photoinduced regeneration rare earth fluorescent microsensor according to claim 1, wherein the lanthanide metal is selected from Eu, Gd, Tb and Dy; the cyclodextrin is selected from β-cyclodextrin or β-cyclodextrin modified with the following groups: carboxylic acid group, phenolic hydroxyl group, alcoholic hydroxyl group, phosphate group, amino group and thiol group.

3. The method for synthesizing the photo-induced regenerated rare-earth fluorescent microsensor according to claim 1 or 2, comprising the following steps: (1) Dissolve cyclodextrin and lanthanide metal salts in ultrapure water, sonicate and stir at room temperature to form a mixed solution; then gradually add powdered SiO2 to the mixed solution in batches and grind until dry; heat, wash and vacuum dry the resulting solid to obtain powdered SiO2@CD-Ln; (2) Disperse powdered SiO2@CD-Ln in ultrapure water, slowly add silver nitrate solution to form a suspension, filter the suspension, wash the filter, heat and dry to obtain powdered SiO2@CD-Ln@Ag2O.

4. The synthetic method according to claim 3, wherein the cyclodextrin is a carboxylic acid, particularly acetic acid, and the modified β-cyclodextrin is obtained as follows: Under alkaline conditions, β-cyclodextrin was reacted with the sodium salt of a monochlorocarboxylic acid (e.g., chloroacetic acid) in ultrapure water overnight. After the reaction solution was cooled to room temperature, the pH was adjusted to 3-5, and a mixed solution of methanol and ethanol was added until the precipitate was completely formed. The white precipitate was collected, washed, and dried to obtain a white powdery carboxylic acid-modified β-cyclodextrin.

5. The synthesis method according to claim 3 or 4, wherein the lanthanide metal salt is its water-soluble salt, such as its chloride or nitrate.

6. The synthesis method according to claim 3 or 4, wherein the molar ratio of cyclodextrin to lanthanide salt is 1:8-15; and the mass ratio of cyclodextrin to powdered SiO2 is 1:5-10.

7. The synthesis method according to claim 3 or 4, wherein the amount of Ag2O is 1.5-5.0 wt% based on the total weight of the photo-induced regenerated rare earth fluorescent microsensor SiO2@CD-Ln@Ag2O.

8. The use of the photo-induced regenerated rare earth fluorescent microsensor according to claim 1 or 2 for detecting tetracycline antibiotic residues in the environment, food, and traditional Chinese medicine.

9. The use according to claim 8, wherein the tetracycline antibiotic is an antibiotic containing a tetracycline core, preferably chlortetracycline, oxytetracycline, tetracycline, tetracycline hydrochloride, chlortetracycline hydrochloride, methacycline, doxycycline, or dimethylaminotetracycline.

10. The use according to claim 8, wherein the photoinduced regenerated rare earth fluorescent microsensor is used at a concentration of 0.2-1.0 mg / mL. -1 It is used in the form of an aqueous dispersion.

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