A terbium-HA nanoaggregate thermal / humidity switching fabric sensor and its preparation method

Abstract

This invention discloses a terbium-HA nanoaggregate-based heat / humidity switching fabric sensor and its preparation method. The method involves the self-assembly of a complex formed by terbium ions and their ligands with natural biological hyaluronic acid to form Tb³⁺-induced hyaluronic acid nanoaggregates with strong green fluorescence. These nanoaggregates are then anchored to the surface of cotton fabric using a coupling agent, resulting in a wearable fluorescent fabric sensor. This fabric emits bright green fluorescence under ultraviolet light excitation and exhibits a unique reversible sensitive switching effect of "heat-activated / humidity-extinguished": fluorescence is quenched when ambient humidity increases and enhanced when temperature increases. Furthermore, the fluorescent fabric sensor demonstrates a rapid, selective, and recognizable fluorescence quenching response to transition metal ions and can be reversibly regenerated through EDTA treatment. The materials used in this invention are environmentally friendly, simple to prepare, and biocompatible, possessing significant application potential in the fields of intelligent wearable environmental sensing, ion detection, and temperature and humidity self-indication.

Description

Technical Field

[0001] This invention relates to the fields of smart sensing materials, fluorescent materials and wearable technology, specifically to a thermally activated / wet-extinguished fluorescent fabric sensor (FCF) based on terbium-hyaluronic acid nanoclusters and its preparation method. Background Technology

[0002] Heavy metal ion pollution is one of the most serious challenges to sustainable development, severely threatening ecological balance and human health. Traditional methods for heavy metal ion detection, such as atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS), while highly sensitive and accurate, suffer from limitations such as expensive instruments, complex operation, cumbersome sample pretreatment, and difficulty in real-time on-site detection. Therefore, developing a rapid, simple, visualized, and wearable method for heavy metal ion detection is of great significance.

[0003] Fluorescent sensing technology has attracted much attention due to its advantages such as high sensitivity, fast response speed, simple operation, and visualization. Among them, lanthanide ion complexes (such as Eu³⁺ and Tb³⁺) have unique luminescent properties, such as long fluorescence lifetimes (microseconds to milliseconds), large Stokes shifts, and narrow-band characteristic emission, making them significant advantages as fluorescent probes in the sensing field. However, most lanthanide complexes have poor water solubility and stability, and some biotoxicity, limiting their application in aquatic environments and biological systems. In addition, integrating fluorescent materials into flexible, wearable fabric substrates to develop smart textiles that combine excellent sensing performance and wearability is a current research hotspot, but existing technologies still face problems such as weak bonding between functional materials and fabrics, poor durability, and limited functionality.

[0004] However, currently, materials based on lanthanide-HA nanoaggregates are mainly used for solution system sensing. There are no reports on how to firmly and stably load them onto fabrics to construct wearable, multi-responsive (temperature, humidity, metal ion) smart sensing fabrics and reveal their unique "heat-on-wet-off" switching effect. Summary of the Invention

[0005] The purpose of this invention is to overcome the key shortcomings of existing technologies, such as poor robustness, poor resistance to humidity and heat, and difficulty in adjusting sensitivity to media, and to provide a thermally activated / wet-extinguished fluorescent fabric sensor based on terbium-hyaluronic acid nanoclusters and its preparation method. This sensor integrates the high efficiency of Tb³⁺ luminescence, the biocompatibility of HA, and the wearability of cotton fabric, achieving sensitive, identifiable, and reversible fluorescence sensing of temperature, humidity, and various metal ions.

[0006] The technical solution of the present invention is as follows: A method for preparing a terbium-HA nanoaggregate heat / humidity switching fabric sensor involves using terbium to induce the formation of bio-hyaluronic acid macromolecules into nanoaggregates, and then using these nanoaggregates to modify the fabric. The modified fabric does not emit light under high humidity, but it emits light again when heated, and is called a heat / humidity switching fluorescent fabric sensor.

[0007] The preparation method specifically includes the following steps: Step 1: Preparation of TH-nanoclusters: Under specific pH, temperature and concentration ranges, terbium salts, organic ligands and hyaluronic acid are mixed in an appropriate ratio in an aqueous phase to obtain nano-aggregates. The coordination between terbium ions and carboxyl groups on the hyaluronic acid molecular chain is used to induce the formation of nano-micelle particles with terbium as the fluorescent luminescence center. Then, an appropriate amount of coupling agent is added to obtain the TH-nanocluster impregnation solution.

[0008] Step 2: Surface grafting reaction of TH-nanoclusters with fabric: Immerse the pretreated pure cotton or blended fabric in a finishing solution containing a coupling agent (liquor ratio 1:20-80), add the TH-nanocluster impregnation solution obtained in Step 1, and under heating conditions, allow the reactive groups in the coupling agent molecules to undergo covalent cross-linking reactions with the hydroxyl groups on the cotton cellulose molecules to form a cross-linked network layer, thereby anchoring the nano-aggregates to the surface of the cotton fabric; Step 3: The grafted fabric obtained in Step 2 is washed and dried to obtain a fluorescent fabric sensor with a reversible thermal on / wet quenching switching effect that quenches fluorescence with increasing humidity and enhances fluorescence with increasing temperature.

[0009] The preparation method described above, step one includes the following steps: Step 1: Dissolve Tb³⁺ source, organic ligand 1, and organic ligand 2 in solvent at a molar ratio of (0.01-1):(0.020-1):(0.01-1), stir at room temperature for 3-5 hours to obtain terbium complex solution; Step 2: Dissolve hyaluronic acid (HA) powder in an acetate-sodium acetate buffer solution with a pH of 3-7 to prepare a hyaluronic acid solution with a concentration of 0.5-1.5 mg / mL; Step 3: Under continuous stirring, the terbium complex solution prepared in Step 1 is slowly added dropwise to the hyaluronic acid solution prepared in Step 2 at a rate of 1-2 mL / min; after the addition is complete, stirring is continued for 0.3-12 hours to allow the two to fully self-assemble through electrostatic attraction; then the pH is adjusted to 7-8 to obtain a homogeneous and clear terbium ion-induced hyaluronic acid nanoaggregates (TH-nanoaggregates) solution; In the preparation method described above, in the first step, the organic ligand 1 and organic ligand 2 are selected from acetylacetone (ACAC), 2,2'-bipyridine (bpy), ethylenediamine (en), oxalate (ox), 8-hydroxyquinoline (8-HQ), triphenylphosphine (PPh3), cyclopentadienyl (Cp), and 1,10-phenanthroline (Phen), and the molar ratio of Tb³⁺: organic ligand 1: organic ligand 2 is (0.01-1):(0.020-1):(0.01-1).

[0010] In the preparation method described above, in the first step, the solvent is a polar compound selected from water, methanol, ethanol, ethylene glycol, and glycerol, and the coordination reaction is carried out at 0℃-75℃ for 0.3-12 hours.

[0011] In the preparation method described above, the hyaluronic acid has a molecular weight of 50-1500 kDa, the nanoaggregates have an average particle size of 20-1200 nm, and a zeta potential of -4.0 to -0.5 mV.

[0012] In the preparation method described above, in the third step, the volume ratio of the terbium complex solution to the hyaluronic acid solution is adjusted according to the mass ratio of Tb³⁺ to HA as (0.5:1) ~ (5:1), wherein the concentration of Tb³⁺ is 0.0001-0.5 mol / L.

[0013] In the preparation method described above, in step two, the coupling agent is selected from solutions of pentaerythritol, glycerol, ethylene glycol, tetraethylsiloxane, and tetramethylsiloxane, wherein the concentration of the coupling agent is 0.1-25 g / L; the grafting reaction temperature is 0-90℃, and the reaction time is 0.2-15 hours.

[0014] The thermally activated / wet-extinguished fluorescent fabric sensor based on terbium-HA nanoaggregates prepared by the method can emit green fluorescence with Tb³⁺ characteristics under ultraviolet light irradiation with a wavelength of 250-390 nm; the fluorescence intensity decreases or is quenched when the ambient humidity increases; and the fluorescence intensity increases when the ambient temperature increases.

[0015] The fluorescent fabric sensor described above can identify, but is not limited to, Fe³⁺, Cu²⁺, Ni²⁺, Mn²⁺, Ru³⁺, and Sn. 4 ⁺, V³⁺, Y³⁺, ​​V³⁺, Sc³⁺, Sn 4 Transition metal ions such as ⁺, Ga³⁺, In³⁺, Sr²⁺, Ca²⁺, and Mg²⁺ exhibit fluorescence quenching responses, and the fluorescence response curves of different metal ions conform to either linear or exponential decay models, respectively. These are used for qualitative identification of ion species, and the fitted curves are classified into linear response modes and nonlinear response modes based on their mathematical characteristics.

[0016] The regeneration method of the fluorescent fabric sensor, namely thermal regeneration or reagent regeneration, allows the sensor to be regenerated by immersing it in an ethylenediaminetetraacetic acid (EDTA) solution after being quenched by metal ions, thus restoring its fluorescence performance; and the sensor to be regenerated by heating and drying after being quenched by humidity.

[0017] A method for fabricating a terbium-hyaluronic acid nanoaggregate heat / humidity switching fabric sensor includes the following steps: Step 1: Dissolve the Tb³⁺ source (such as TbCl₃·6H₂O), organic ligand 1, and organic ligand 2 in a solvent at a molar ratio of (0.01-1):(0.020-1):(0.01-1). Stir the mixture at room temperature for 3-5 hours to obtain a complex solution. This complex is positively charged due to Tb³⁺. Step 2: Dissolve hyaluronic acid (HA) powder in a buffer solution with a pH of 3-7 to prepare a hyaluronic acid solution with a concentration of 0.5-1.5 mg / mL. The carboxyl groups on the HA molecular chain give it a negative charge. The buffer solution used can be, but is not limited to, phosphoric acid, acetic acid, dilute hydrochloric acid, citric acid, etc.

[0018] Step 3: Under continuous stirring, the terbium complex solution prepared in Step 1 was slowly added dropwise to the hyaluronic acid solution prepared in Step 2 at a rate of 1-2 mL / min. After the addition was complete, stirring was continued for 0.3-12 hours to allow the two to fully self-assemble through electrostatic attraction. Subsequently, the pH was adjusted to 7-8 to obtain a homogeneous and clear terbium ion-induced hyaluronic acid nanoaggregates (TH-nanoaggregates) solution. TEM and DLS characterization showed that the TH-nanoaggregates were uniform spherical particles with a particle size of approximately 20-1200 nm, and their Zeta potential was negative, confirming that HA was successfully encapsulated on the outside of the Tb complex core. Step 4: Pretreatment of cotton fabric: Immerse the cotton fabric in a boiling water bath containing 10 g / L sodium hydroxide at a ratio of 1:50, and boil for an appropriate time to remove impurities from the fiber surface. Then wash and dry thoroughly. Step 5: Preparation of finishing solution: The coupling agent is selected from aqueous solutions of pentaerythritol, glycerol, ethylene glycol, tetraethylsiloxane, tetramethylsiloxane, etc., with a concentration of 0.1-25 g / L; the grafting reaction temperature is 0-90℃, and the reaction time is 0.2-15 hours. The pretreated cotton fabric is immersed in the finishing solution (liquor ratio 1:50), heated to 90℃ for 1 hour, and then the TH-nanopolymer solution prepared in step 3 is added. The temperature is lowered to 80℃, and the reaction continues for 2-5 hours. After the reaction is complete, the fabric is removed, rolled, pre-dried (80℃, 10-150 min), and baked (130-210℃, 2 min) to obtain the fluorescent fabric sensor. XPS and SEM analyses show that the TH-nanopolymers are anchored to the cotton fiber surface through the cross-linking effect of the coupling agent.

[0019] The fluorescent fabric sensor prepared in this invention emits strong green fluorescence (545 nm, corresponding to Tb³⁺) under 365 nm ultraviolet light irradiation. 5 D4→ 7 F5 jump).

[0020] The fluorescent fabric sensor prepared by this invention has the following excellent sensing performance: Thermal-on / wet-off reversible sensitive switching effect: At constant temperature, the fluorescence intensity of the fluorescent fabric sensor gradually decreases with increasing relative humidity (20% RH → 90% RH), exhibiting a "wet-off" effect, attributed to the enhanced nonradiative transitions of water molecules through OH vibrational coupling. At constant humidity, the fluorescence intensity of the fluorescent fabric sensor gradually increases with increasing ambient temperature (room temperature - 70℃), exhibiting a "thermal-on" effect, attributed to the evaporation of water molecules and improved energy transfer efficiency. This effect is highly reversible; the fluorescence can be completely recovered after drying.

[0021] Selective recognition of multiple metal ions: Fluorescent fabric sensor pairs include, but are not limited to, Fe³⁺, Cu²⁺, Ni²⁺, Mn²⁺, Ru³⁺, and Sn. 4 ⁺, V³⁺, Y³⁺, ​​V³⁺, Sc³⁺, Sn 4 Various transition metal ions, including Fe³⁺, Ga³⁺, In³⁺, Sr²⁺, Ca²⁺, and Mg²⁺, exhibit sensitive fluorescence quenching responses. By analyzing the characteristics of fluorescence intensity versus ion concentration curves, linear response modes (e.g., Fe³⁺, Ru³⁺, In³⁺, R²>0.94) and nonlinear response modes (e.g., Cu²⁺, Ni²⁺, Mn²⁺) can be distinguished, providing a new strategy for rapid qualitative matching of ion species. Fluorescence lifetime tests indicate that the quenching mechanism is primarily dynamic quenching.

[0022] Excellent reversible regeneration performance: Fluorescent fabric sensors quenched by metal ions can be regenerated by immersion in a 0.03 MEDTA solution. EDTA competitively chelates metal ions, restoring fluorescence (the recovery rate is slightly lower for some ions such as Fe³⁺, V³⁺, and Ru³⁺ due to accompanying oxidation). Fluorescent fabric sensors quenched by high humidity can be completely restored by heating and drying. The material has recycling potential.

[0023] The greatest advantage and beneficial effect of this invention compared to the prior art is: Multifunctional integration: For the first time, triple response to temperature, humidity and multiple metal ions was achieved on the same fabric sensor, and in particular, a unique “heat-on-wet-off” switching effect was discovered.

[0024] High sensitivity and selectivity: The fluorescence response to metal ions exhibits distinguishable characteristic curves, which facilitates rapid qualitative identification.

[0025] Green, environmentally friendly, and biocompatible: It uses natural biological hyaluronic acid (HA) and environmentally friendly coupling agents, avoiding the use of toxic reagents such as formaldehyde. The material has good biocompatibility and is suitable for wearable applications.

[0026] Simple preparation and good stability: The preparation process is mild through self-assembly and covalent grafting, the functional layer is firmly bonded to the substrate and has good folding resistance.

[0027] Reversible regeneration: The sensor can be regenerated through simple processing, reducing the cost of use. Attached Figure Description

[0028] Figure 1 This is a transmission electron microscope (TEM) image of the TH-nanoclusters prepared in this invention.

[0029] Figure 2 This is a scanning electron microscope (SEM) image of the fluorescent fabric sensor prepared according to the present invention.

[0030] Figure 3 This is a schematic diagram of the thermal on / wet off switching effect of the fluorescent fabric sensor of the present invention.

[0031] Figure 4 This is a fluorescence response curve of the fluorescent fabric sensor of the present invention to different metal ions.

[0032] Figure 5 The fluorescent fabric sensor of the present invention has fluorescence emission spectra under different humidity levels.

[0033] Figure 6 The fluorescent fabric sensor of the present invention exhibits fluorescence emission spectra at different temperatures.

[0034] Figure 7 This is the fluorescence spectrum of the fluorescent fabric sensor of the present invention after quenching with metal ions and regenerating with EDTA. Detailed Implementation

[0035] The present invention will be described in detail below with reference to specific embodiments. Example 1

[0036] (1) Weigh 0.373 g TbCl3·6H2O (1 mmol) and dissolve it in 20 mL of solvent. Add 0.300 g acetylacetone (3 mmol) and 0.198 g 1,10-phenanthroline (1 mmol) in ethanol solution respectively. Stir at room temperature for 2 hours to obtain colorless TbCl3·6H2O. 3+ b-complex transparent solution.

[0037] (2) Prepare a dilute hydrochloric acid buffer solution with pH=5. Dissolve 10 mg of hyaluronic acid (HA) in 10 mL of buffer solution and stir for 5 hours until completely dissolved. While stirring, add the entire Tb complex solution obtained in step 1 dropwise to the HA solution at a rate of approximately 1 mL / min. After the addition is complete, continue stirring for 2 hours. Adjust the pH to 7.5 to obtain a clear TH-nano-aggregate solution.

[0038] (3) Cut the cotton cloth into 5×5 cm², immerse it in boiling water containing 10 g / L NaOH (bath ratio 1:50), boil for 30 minutes, then wash with hot water and deionized water and air dry.

[0039] (4) Prepare 50 mL of pentaerythritol finishing solution, with a pentaerythritol coupling agent concentration of 2.5 g / L. Immerse the cotton fabric pretreated in step (3) in the solution (bath ratio 1:50) and treat at 90℃ for 1 h. Then add 5 mL of TH-nano-aggregate solution and continue the reaction at 80℃ for 3 h. Remove the fabric, wash it with deionized water, pre-dry it at 80℃ for 60 min, and bake it at 190℃ for 25 min to obtain the fluorescent fabric sensor.

[0040] (5) Under a 365 nm UV lamp, the fluorescent fabric sensor exhibits strong green fluorescence. When the fluorescent fabric sensor is placed in a constant temperature chamber at 25℃ and different humidity levels (20%-90% RH) for 20 min, the fluorescence intensity decreases with increasing humidity. When the fluorescent fabric sensor is placed in a constant temperature chamber at 45% RH and different temperatures (25-70℃) for 20 min, the fluorescence intensity increases with increasing temperature. When the fluorescent fabric sensor is immersed in solutions of different metal ions (Fe³⁺, Cu²⁺, Ni²⁺, etc.) at 1×10⁻³ mol / L for 10 min, and then dried, the fluorescence is significantly quenched, with different quenching curve characteristics. After quenching, the fluorescent fabric sensor is immersed in 0.03 M EDTA solution for 30 min, and the fluorescence can be partially or mostly recovered.

[0041] Examples 2-6 Table 1 Parameters of Examples 2-6

[0042] Following the steps of Example 1, only the concentrations of Tb³⁺ (0.0001-0.5 mol / L), HA (0.5-1.5 mg / mL), and coupling agent (0.1-25 g / L) during the preparation of TH-nanopolymers were changed. Optimization results showed that when the Tb³⁺ concentration was 0.01 mol / L, the HA concentration was 1 mg / mL, and the coupling agent concentration was 2.5 g / L, the prepared fluorescent fabric sensor exhibited the highest fluorescence intensity, the most uniform distribution, and the best overall performance.

[0043] Comparative Example 1 Referring to Example 1, but omitting HA, we directly attempted to graft the complex onto cotton fabric. The results showed that, due to the poor water solubility and tendency to aggregate of the Tb complex, a uniform fluorescent coating could not be formed on the fabric; the fluorescence intensity was low and extremely unevenly distributed, and the sensitivity to metal ions was significantly reduced.

[0044] Comparative Example 2 Referring to Example 1, but omitting the coupling agent, the TH-nano-aggregate solution was directly blended with the pretreated cotton fabric and heated. The folding resistance test showed that after 50 folds and washes, the fabric's fluorescence intensity decreased by more than 80%, indicating that the TH-nano-aggregates only physically adsorbed onto the fabric, resulting in weak binding force and poor durability.

[0045] Figure 1 This is a transmission electron microscope (TEM) image of the TH-nanoclusters prepared in this invention.

[0046] like Figure 1 As shown, the terbium ion-induced hyaluronic acid nanoaggregates (TH-nanoaggregates) prepared in this invention exhibit uniformly distributed, regular spherical nanoparticles with consistent particle size, good dispersibility, and no obvious agglomeration. Dynamic light scattering analysis revealed an average hydrated particle size of approximately 100 nm, indicating that the negatively charged hyaluronic acid (HA) and the positively charged Tb(ACAC)3Phen complex successfully self-assembled via electrostatic attraction, forming a stable core-shell structure. This provides a structural basis for subsequent uniform loading onto cotton fabric surfaces.

[0047] Figure 2 This is a scanning electron microscope (SEM) image of the fluorescent fabric sensor prepared according to the present invention. Figure 2 As shown, after treatment with optimized concentrations of TH-nanopolymers, the cotton fiber surface exhibits a uniform and dense distribution of TH-nanopolymer particles. These particles are of uniform size, well-dispersed, and show no aggregation. Compared to the untreated smooth cotton fiber surface, this morphology confirms that the TH-nanopolymers are firmly anchored to the cotton fiber surface through covalent cross-linking with the coupling agent, forming a uniform fluorescent functional layer. This ensures that the sensor has stable luminescent sites and consistent macroscopic fluorescence emission.

[0048] Figure 3 This is a schematic diagram of the thermal on / wet off switching effect of the fluorescent fabric sensor of the present invention. Figure 3This paper visually demonstrates the response behavior and reversibility of the fluorescence intensity of the fluorescent fabric sensor (FCF) of this invention in response to changes in ambient humidity and temperature. At a constant temperature, as the relative humidity increases (20%RH→90%RH), the fluorescence intensity gradually decreases, exhibiting a "wet quenching" effect. At a constant humidity, as the temperature increases (room temperature→70℃), the fluorescence intensity gradually increases, exhibiting a "thermal quenching" effect. This effect is attributed to enhanced nonradiative transitions due to OH vibrational coupling of water molecules, elimination of quenching through water evaporation, and improved energy transfer efficiency. Furthermore, it can be completely recovered after heating and drying, demonstrating excellent reversible and sensitive switching characteristics.

[0049] Figure 4 This is a fluorescence response curve of the fluorescent fabric sensor of the present invention to different metal ions. Figure 4 As shown, the fluorescent fabric sensor of the present invention supports Fe³⁺, Y³⁺, ​​Ru³⁺, In³⁺, V³⁺, Sc³⁺, Ga³⁺, Mg²⁺, Sr²⁺ (Figure a) as well as Ni²⁺, Cu²⁺, and Sn. 4 Various transition metal ions, including ⁺, Mn²⁺, and Ca²⁺ (Figure b), exhibited sensitive fluorescence quenching responses, while alkaline earth metal ions (Ca²⁺, Mg²⁺, and Sr²⁺) showed no significant response. Based on the curve characteristics, they can be distinguished into a linear response mode (R²>0.94, conforming to the Stern-Volmer quenching model) and a nonlinear response mode (conforming to an exponential decay model, where Ni²⁺ exhibits a "first enhancement, then quenching" biphasic response). This differentiated response characteristic provides a reliable criterion for rapid qualitative identification of ion species.

[0050] Figure 5 The images show the fluorescence emission spectra of the fluorescent fabric sensor of this invention under different humidity levels. Figure 5 As shown, under constant temperature of 25℃, when the relative humidity gradually increases from 20% to 90%, the characteristic fluorescence emission intensity of the fluorescent fabric sensor of this invention at 545nm shows a regular decrease, while the peak shape and position remain unchanged. This phenomenon indicates that the fluorescence quenching by water molecules is a non-radiative energy dissipation process that does not damage the structure of the luminescent center. Real-time and quantitative detection of ambient humidity can be achieved by monitoring changes in fluorescence intensity.

[0051] Figure 6 The images show the fluorescence emission spectra of the fluorescent fabric sensor of this invention at different temperatures. Figure 6 As shown, under constant humidity (45% RH) conditions, as the ambient temperature gradually increases from room temperature to 70°C, the characteristic fluorescence emission intensity of the fluorescent fabric sensor of this invention at 545 nm exhibits a regular increase, while the peak shape and position remain stable. This "thermal-start" effect originates from the increased temperature promoting water evaporation, improving the ligand → Tb³⁺ energy transfer efficiency, and optimizing the coordination environment of the nano-aggregates. Combined with heat drying treatment, fluorescence can be completely restored, confirming the feasibility of thermal regeneration.

[0052] Figure 7 This is the fluorescence spectrum of the fluorescent fabric sensor of the present invention after quenching with metal ions and regenerating with EDTA. (Example:) Figure 7 As shown, the fluorescent fabric sensor, after being quenched by Co²⁺ (Fig. a) and In³⁺ (Fig. b) metal ions, exhibits effective recovery of characteristic fluorescence emission (approximately 50%) after immersion in a 0.03M EDTA solution. EDTA, as a strong chelating agent, competitively captures metal ions bound to TH-nanopolymers, forming soluble complexes that are then removed from the fiber surface. This reversible regeneration strategy is simple to operate, operates under mild conditions, and significantly improves the sensor's recyclability.

[0053] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a terbium-HA nanoaggregate thermal / humidity switching fabric sensor, characterized in that, Terbium is used to induce the formation of nano-aggregates from biological hyaluronic acid macromolecules. These nano-aggregates are then used to modify fabrics, resulting in modified fabrics that do not emit light when quenched under high humidity, but emit light again when heated. This is called a heat / humidity switch fluorescent fabric sensor.

2. The preparation method according to claim 1, characterized in that, The preparation method specifically includes the following steps: Step 1: Preparation of TH-nano-aggregate impregnation solution: Under specific pH, temperature and concentration ranges, terbium salt, organic ligand and hyaluronic acid are mixed in an appropriate ratio in the aqueous phase to obtain nano-aggregates. The coordination between terbium ions and carboxyl groups on the hyaluronic acid molecular chain is used to induce the formation of nano-micelle particles with terbium as the fluorescence luminescence center. Then, an appropriate amount of coupling agent is added to obtain the TH-nano-aggregate impregnation solution. Step 2: Surface grafting reaction of TH-nanoclusters with fabric: Immerse the pretreated pure cotton or blended fabric in a finishing solution containing a coupling agent (liquor ratio 1:20-80), add the TH-nanocluster impregnation solution obtained in Step 1, and under heating conditions, allow the reactive groups in the coupling agent molecules to undergo covalent cross-linking reactions with the hydroxyl groups on the cotton cellulose molecules to form a cross-linked network layer, thereby anchoring the nano-aggregates to the surface of the cotton fabric; Step 3: The grafted fabric obtained in Step 2 is washed and dried to obtain a fluorescent fabric sensor with a reversible thermal on / wet quenching switching effect that quenches fluorescence with increasing humidity and enhances fluorescence with increasing temperature.

3. The preparation method according to claim 2, characterized in that, Step one includes the following steps: Step 1: Dissolve Tb³⁺ source, organic ligand 1, and organic ligand 2 in solvent at a molar ratio of (0.01-1):(0.020-1):(0.01-1), stir at room temperature for 3-5 hours to obtain terbium complex solution; Step 2: Dissolve hyaluronic acid (HA) powder in a solution with pH=3-7 to prepare a hyaluronic acid solution with a concentration of 0.5-1.5 mg / mL; Step 3: Under continuous stirring, the terbium complex solution prepared in Step 1 is slowly added dropwise to the hyaluronic acid solution prepared in Step 2 at a rate of 1-2 mL / min; after the addition is complete, stirring is continued for 0.3-12 hours to allow the two to fully self-assemble through electrostatic attraction; then the pH is adjusted to 7-8 to obtain a homogeneous and clear terbium ion-induced hyaluronic acid nanoaggregates (TH-nanoaggregates) solution.

4. The preparation method according to claim 3, characterized in that, In the first step, the organic ligands 1 and 2 are selected from acetylacetone (ACAC), 2,2'-bipyridine (bpy), ethylenediamine (en), oxalate (ox), 8-hydroxyquinoline (8-HQ), triphenylphosphine (PPh3), cyclopentadienyl (Cp), 1,10-phenanthroline (Phen), and Tb. ³⁺ The molar ratio of organic ligand 1 to organic ligand 2 is (0.01-1):(0.020-1):(0.01-1).

5. The preparation method according to claim 3, characterized in that, In the first step, the solvent is a polar compound selected from water, methanol, ethanol, ethylene glycol, and glycerol. The coordination reaction is carried out at 0℃-75℃ for 0.3-12 hours.

6. The preparation method according to claim 3, characterized in that, In the third step, the volume ratio of the terbium complex solution to the hyaluronic acid solution is adjusted according to the mass ratio of Tb³⁺ to HA as (0.5:1) ~ (5:1), wherein the concentration of Tb³⁺ is 0.0001-0.5 mol / L.

7. The preparation method according to claim 1, characterized in that, In step two, the coupling agent includes, but is not limited to, solutions of tetraethylsiloxane, glycerol, ethylene glycol, pentaerythritol, tetramethylsiloxane, etc., wherein the concentration of the coupling agent is 0.1-25 g / L; the grafting reaction temperature is 0-90℃, and the reaction time is 0.2-15 hours.

8. The thermally activated / wet-extinguished fluorescent fabric sensor based on terbium-HA nanoclusters prepared by any one of claims 1-7, characterized in that, Under ultraviolet light irradiation with wavelengths of 250-390 nm, it can emit green fluorescence with Tb³⁺ characteristics; the fluorescence intensity decreases or is quenched when the ambient humidity increases; and the fluorescence intensity increases when the ambient temperature increases.

9. The application of the fluorescent fabric sensor according to claim 8 in identifying transition metal ions, characterized in that, The sensor includes, but is not limited to, Fe. ³⁺ Cu ²⁺ Ni ²⁺ Mn ²⁺ Ru ³⁺ Sn 4⁺ V ³⁺ Y ³⁺ V ³⁺ , Sc ³⁺ Sn 4⁺ Ga ³⁺ In ³⁺ , Sr ²⁺ Ca ²⁺ , and Mg ²⁺ Transition metal ions exhibit fluorescence quenching responses, and the fluorescence response curves of different metal ions conform to either linear or exponential decay models, respectively. These are used for qualitative identification of ion species, and the fitted curves are classified into linear and nonlinear response modes based on their mathematical characteristics.

10. The method for regenerating a fluorescent fabric sensor according to claim 8, characterized in that, Sensors that have been quenched by metal ions can be regenerated by immersing them in an ethylenediaminetetraacetic acid (EDTA) solution to restore their fluorescence performance, either by heat or by reagent regeneration. Sensors that have been quenched by humidity can be regenerated by heating and drying.

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