Quenching agent synergetic stable dye-sensitized up-conversion nanoparticles and preparation method thereof

Abstract

The invention discloses a preparation method of quencher synergistic stable dye sensitized up-conversion nanoparticles, which specifically comprises the following steps: mixing up-conversion nanoparticles with an N, N-dimethylformamide solution of nitrate tetrafluoroborate, shaking, standing and centrifuging to obtain surface modified up-conversion nanoparticles; mixing the surface-modified up-conversion nanoparticles, a dye and a solvent, and oscillating to obtain dye-sensitized up-conversion nanoparticles; and mixing the dye-sensitized up-conversion nanoparticles, a quencher and a solvent, and oscillating to obtain the dye-sensitized up-conversion nanoparticles synergistically stabilized by the quencher. The organic dye (IR806) is grafted on the surface of the up-conversion nanoparticle for sensitization luminescence, the luminescence performance of the up-conversion nanoparticle is improved, and the stability of the IR806 sensitized up-conversion nanoparticle is synergistically enhanced by adopting the quencher, so that the up-conversion nanoparticle has a wide application prospect in the aspects of biomarker, imaging application and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of rare earth luminescent material preparation, and particularly relates to a preparation method of quencher-synergistically stabilized dye-sensitized upconversion nanoparticles, and also relates to the quencher-synergistically stabilized dye-sensitized upconversion nanoparticles. Background Art

[0002] Dye-sensitized upconversion nanoparticle systems have shown great application potential in the fields of bioimaging, photodynamic therapy, and optical sensing due to their efficient multi-photon response characteristics under near-infrared light excitation. This system combines organic dyes with broad-spectrum absorption with UCNPs, and utilizes the efficient capture ability of dye molecules for excitation photons, breaking through the inherent narrow-band absorption limitations of traditional rare-earth-doped UCNPs and achieving an order of magnitude increase in the luminescence quantum yield. However, during the laser excitation process, the triplet to singlet energy transfer path generated by the dye molecules will not only cause up to 80% of the energy to be dissipated in the form of non-radiative transitions, but will also trigger a photosensitization chain reaction. The excited-state dye interacts with the surrounding dissolved oxygen to produce singlet oxygen ( 1 O2), superoxide radicals (O 2⁻ ·) and other highly reactive oxygen species (ROS). These reactive species, while attacking biological targets, also irreversibly oxidatively degrade the dye molecules themselves, causing rapid photobleaching of the sensitized system. This dual photodamage mechanism leads to insufficient photostability, severely limiting the stability and application of dye-sensitized UCNPs. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method of dye-sensitized upconversion nanoparticles by synergistically stabilizing the dye-sensitized upconversion nanoparticles, thereby improving the stability of the dye-sensitized upconversion nanoparticles.

[0004] Another object of the present invention is to provide a quencher that synergistically stabilizes dye-sensitized upconversion nanoparticles.

[0005] The technical solution adopted by the present invention is a method for preparing quencher-synergistically stabilized dye-sensitized upconversion nanoparticles, which is specifically implemented according to the following steps: Step 1, synthesizing upconversion nanoparticles; Step 2, mixing the upconversion nanoparticles obtained in step 1 with a solution of tetrafluoroborate in N,N-dimethylformamide, shaking, standing, and centrifuging to obtain surface-modified upconversion nanoparticles; Step 3, mixing the surface-modified upconversion nanoparticles, the dye, and the solvent, and shaking to obtain dye-sensitized upconversion nanoparticles; Step 4: mixing the dye-sensitized upconversion nanoparticles obtained in step 3, the quencher and the solvent, and shaking to obtain the quencher-synergistically stabilized dye-sensitized upconversion nanoparticles.

[0006] The present invention is also characterized in that: In step 1, specifically: Step 1.1, YCl3·6H2O, YbCl3·6H2O, and ErCl3·6H2O are dissolved in methanol, followed by the addition of octadecene and oleic acid, mixed uniformly, and the resulting mixture is sonicated; the mixture is then stirred and heated, and cooled to room temperature to form an oleic acid-coated precursor mixture; Step 1.2, adding the sodium hydroxide-ammonium fluoride-methanol mixture to the precursor mixture and stirring for 20-30 minutes; stirring and heating the precursor mixture again at a temperature of 120-150° C. for 20-30 minutes, and then cooling it to room temperature again; In step 1.3, the precursor mixture obtained in step 1.2 is evacuated at room temperature, filled with nitrogen, and the evacuation-nitrogen filling is repeated three times to ensure that oxygen is removed from the system; then, the precursor mixture is heated at a temperature of 280-310°C for 80-120 minutes; cooled to room temperature, centrifuged, and the obtained nanoparticles are dispersed in a mixed solution of cyclohexane and ethanol, centrifuged, and the dispersion-centrifugation is repeated three times. Finally, the collected nanoparticles are stored in the cyclohexane solution.

[0007] In step 1.1, the mass ratio of YCl3·6H2O, YbCl3·6H2O, ErCl3·6H2O, octadecene and oleic acid is 70-80:15-25:1-2:6-8:10-15; the ultrasonic treatment time is 5-15 min; the stirring rate is 400-700 rpm, the heating temperature is 130-150°C, and the heating time is 20-30 min.

[0008] In step 1.2, the preparation process of the sodium hydroxide-ammonium fluoride-methanol mixed solution is as follows: sodium hydroxide, ammonium fluoride and methanol are mixed and ultrasonically dispersed to obtain a sodium hydroxide-ammonium fluoride-methanol mixed solution; the mass ratio of sodium hydroxide to ammonium fluoride is 6-8:10-15; the ultrasonic dispersion temperature is 15-30°C and the time is 10-30 minutes.

[0009] In step 2, specifically, the upconversion nanoparticles obtained in step 1 are mixed with a solution of tetrafluoroborate in N,N-dimethylformamide, shaken on a shaker, and allowed to stand for 20-40 minutes. The supernatant is aspirated and discarded, toluene and cyclohexane are added to the DMF layer, centrifuged, the supernatant is removed, ethanol is added, and centrifuged. The addition of ethanol and centrifugation are repeated three times to obtain surface-modified upconversion nanoparticles.

[0010] In step 3, specifically: The upconversion nanoparticles prepared in step 2 were dispersed in DMF to obtain a nanoparticle suspension with a concentration of 1-2 mg / mL; the IR806 dye powder was dissolved in DMF until it was fully dissolved to obtain a dye mother liquor with a concentration of 500-1000 μmol / L; the nanoparticle suspension was mixed with the dye mother liquor, and then transferred to a light-proof glass bottle and placed in a shaker for light-proof shaking to finally obtain dye-sensitized upconversion nanoparticles.

[0011] In step 4, specifically: The dye-sensitized upconversion nanoparticles obtained in step 3 are dispersed in DMF solvent to obtain a dye-sensitized UCNPs suspension; the quencher is dissolved in DMF solvent, and after complete dissolution, a quencher solution with a concentration of 1-1000 mM is obtained; the dye-sensitized UCNPs suspension is mixed with the quencher solution, and then the mixed solution is transferred to a light-proof glass bottle and placed in a shaker for light-proof shaking to obtain quencher-synergistically stabilized dye-sensitized upconversion nanoparticles.

[0012] The quencher is specifically any one or two of nitrobenzyl alcohol, quinoline dimethacrylate, propyl gallate, ascorbic acid, and 2-mercaptoethanol.

[0013] Another technical solution adopted by the present invention is to prepare upconversion nanoparticles using a preparation method in which a quencher cooperates to stabilize dye-sensitized upconversion nanoparticles.

[0014] The beneficial effects of the present invention are: The present invention improves the luminescence performance of upconversion nanoparticles by grafting an organic dye (IR806) on the surface of upconversion nanoparticles to sensitize luminescence, and uses a quencher to synergistically enhance the stability of IR806-sensitized upconversion nanoparticles, making it have broad application prospects in biomarkers and imaging applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a TEM image of the upconversion nanoparticles synthesized in Example 1; Figure 2 This is a graph showing the luminescence stability of dye-sensitized upconversion nanoparticles prepared using quencher NBA solutions with different concentrations, showing the intensity changes over time. Figure 3 This is a graph showing the luminescence stability of dye-sensitized upconversion nanoparticles prepared using quencher Trolox solutions with different concentrations, showing the intensity changes over time. Figure 4 This is a stability test curve of the dye-sensitized upconversion nanoparticles prepared in Examples 3-6. DETAILED DESCRIPTION

[0016] The present invention will be described in detail below with reference to specific embodiments and the accompanying drawings.

[0017] The preparation method of the quencher-synergistically stabilized dye-sensitized upconversion nanoparticles of the present invention is specifically implemented according to the following steps: Step 1, synthesis of upconversion nanoparticles; specifically: Step 1.1, YCl3·6H2O, YbCl3·6H2O, and ErCl3·6H2O are dissolved in methanol, followed by the addition of octadecene and oleic acid, and the mixture is thoroughly mixed. The resulting mixture is ultrasonically treated for 5-15 minutes; the mixture is then stirred and heated at a stirring rate of 400-700 rpm at a temperature of 130-150°C for 20-30 minutes to remove methanol and water molecules, and then cooled to room temperature to form an oleic acid-coated precursor mixture; The mass ratio of YCl3·6H2O, YbCl3·6H2O, ErCl3·6H2O, octadecene and oleic acid is 70-80:15-25:1-2:6-8:10-15; In step 1.2, a sodium hydroxide-ammonium fluoride-methanol mixture is added to the precursor mixture and stirred for 20-30 minutes; the precursor mixture is stirred and heated again at a stirring rate of 400-600 rpm, a heating temperature of 120-150° C., and a heating time of 20-30 minutes, and then cooled to room temperature again; The preparation process of the sodium hydroxide-ammonium fluoride-methanol mixed solution is as follows: sodium hydroxide, ammonium fluoride and methanol are mixed and ultrasonically dispersed to obtain the sodium hydroxide-ammonium fluoride-methanol mixed solution; The mass ratio of sodium hydroxide to ammonium fluoride is 6-8:10-15; the ultrasonic dispersion temperature is 15-30°C and the time is 10-30 minutes; Step 1.3: Vacuum the precursor mixture obtained in step 1.2 at room temperature for 10-20 minutes, fill it with nitrogen, and repeat the vacuum-filling and nitrogen-filling three times to ensure that oxygen is removed from the system; The precursor mixture is then heated to 280-310°C for 80-120 minutes, cooled to room temperature, and centrifuged at 10,000 rpm for 15 minutes. The resulting nanoparticles are then dispersed in a 1:1 volume ratio of cyclohexane and ethanol. The mixture is then centrifuged again at 10,000 rpm for 15 minutes. This dispersion and centrifugation cycle is repeated three times to ensure the purity of the nanoparticles. Finally, the collected nanoparticles are stored in the cyclohexane solution for subsequent use.

[0018] Step 2, performing surface modification treatment on the upconversion nanoparticles (UCNPs) obtained in step 1; specifically: The oleic acid-coated upconversion nanoparticles dispersed in cyclohexane were mixed with a 1 mg / mL solution of nitric acid tetrafluoroborate (NOBF4) in N, N-dimethylformamide in a volume ratio of 1:1. The mixture was shaken on a shaker at 200 rpm for 15 minutes to promote the extraction of UCNPs from the cyclohexane layer into the DMF layer. After standing for 20-40 minutes, the supernatant was aspirated and discarded. Toluene and cyclohexane (mixed in a volume ratio of 1:1) were added to the DMF layer and centrifuged at 10,000 rpm for 15 minutes. After centrifugation, the supernatant was removed, ethanol was added and centrifuged at 10,000 rpm for 15 minutes. The addition of ethanol and centrifugation were repeated three times to obtain surface-modified upconversion nanoparticles. Step 3, preparation of dye-sensitized upconversion nanoparticles; The upconversion nanoparticles (UCNPs) prepared in step 2 were dispersed in N,N-dimethylformamide (DMF) solvent to obtain a nanoparticle suspension with a concentration of 1-2 mg / mL. IR806 dye powder was dissolved in DMF and sonicated for 10 minutes to fully dissolve it, obtaining a dye mother solution with a concentration of 500-1000 μmol / L. The nanoparticle suspension was mixed with the dye mother solution, then transferred to a light-proof glass bottle and placed in a constant temperature shaker (25°C, 200 rpm) for 5 min in the dark to promote the anchoring of the dye molecules on the nanoparticle surface. Finally, dye-sensitized upconversion nanoparticles were obtained, which were sealed and stored in the dark at 4°C until use. Step 4, dispersing the dye-sensitized upconversion nanoparticles obtained in step 3 in DMF solvent to obtain a dye-sensitized UCNPs suspension; dissolving the quencher in DMF solvent and ultrasonicating for 10 min to ensure its complete dissolution to obtain a quencher solution with a concentration of 1-1000 mM; The quencher is specifically any one or two of nitrobenzyl alcohol, quinoline dimethacrylate, propyl gallate, ascorbic acid, and 2-mercaptoethanol.

[0019] The dye-sensitized UCNPs suspension was mixed with the quencher solution, and then the mixed solution was transferred to a light-proof glass bottle and placed in a constant temperature shaker. It was shaken in the dark at 25°C and 200 rpm for 5 min to obtain stable quencher-functionalized dye-sensitized upconversion nanoparticles.

[0020] The nitro group (-NO2) in the p-nitrobenzyl alcohol (NBA) molecule is a strong electron-withdrawing group that significantly alters the electron distribution of the benzene ring through a conjugation effect, enhancing the molecule's electron affinity. This property enables it to interact with excited-state molecules through a photoinduced electron transfer (PET) mechanism, rapidly capturing triplet energy or electrons, thereby quenching highly reactive triplet species. Quinodimethacrylate (Trolox) is a water-soluble vitamin E analog. Its mechanism of action primarily relies on scavenging free radicals and inhibiting oxidative chain reactions, quenching excited triplet states through electron transfer, thereby reducing photobleaching.

[0021] Example 1 The preparation method of the quencher-synergistically stabilized dye-sensitized upconversion nanoparticles of the present invention is specifically implemented according to the following steps: Step 1, synthesis of upconversion nanoparticles; specifically: Step 1.1, YCl3·6H2O, YbCl3·6H2O, and ErCl3·6H2O were dissolved in methanol, followed by the addition of octadecene and oleic acid, and the mixture was thoroughly mixed. The resulting mixture was ultrasonically treated for 5 minutes. The mixture was then stirred and heated at a stirring rate of 500 rpm, a heating temperature of 130°C, and a heating time of 20 minutes, and then cooled to room temperature to form an oleic acid-coated precursor mixture. The mass ratio of YCl3·6H2O, YbCl3·6H2O, ErCl3·6H2O, octadecene, and oleic acid is 75:15:1:6:10; In step 1.2, a sodium hydroxide-ammonium fluoride-methanol mixture was added to the precursor mixture and stirred for 20 minutes. The precursor mixture was stirred and heated again at a stirring rate of 400 rpm, a heating temperature of 120° C., and a heating time of 20 minutes, and then cooled to room temperature again. The preparation process of the sodium hydroxide-ammonium fluoride-methanol mixture is as follows: 2.5 mmol of sodium hydroxide, 4 mmol of ammonium fluoride and 5 mL of methanol are mixed and ultrasonically dispersed to obtain a sodium hydroxide-ammonium fluoride-methanol mixture; the ultrasonic dispersion temperature is 25°C and the time is 10 minutes; In step 1.3, the precursor mixture obtained in step 1.2 was evacuated at room temperature for 10 minutes and filled with nitrogen. This evacuation and nitrogen filling cycle was repeated three times to ensure the removal of oxygen from the system. Subsequently, the precursor mixture was heated to 280°C for 90 minutes, cooled to room temperature, and centrifuged at 10,000 rpm for 15 minutes. The resulting nanoparticles were redispersed in a 1:1 volume ratio cyclohexane / ethanol mixture and centrifuged again at 10,000 rpm for 15 minutes. This dispersion and centrifugation cycle was repeated three times to ensure the purity of the nanoparticles. Finally, the collected nanoparticles were stored in the cyclohexane solution for subsequent use.

[0022] Figure 1 This is a TEM image of the upconversion nanoparticles synthesized in Example 1. It can be found that they are evenly distributed and have a suitable size, all around 20 nm.

[0023] Step 2, performing surface modification treatment on the upconversion nanoparticles (UCNPs) obtained in step 1; specifically: The oleic acid-coated upconversion nanoparticles dispersed in cyclohexane were mixed with a 1 mg / mL solution of nitric acid tetrafluoroborate (NOBF4) in N, N-dimethylformamide in a volume ratio of 1:1. The mixture was shaken on a shaker at 200 rpm for 15 minutes to promote the extraction of UCNPs from the cyclohexane layer into the DMF layer. After standing for 20 minutes, the supernatant was aspirated and discarded. Toluene and cyclohexane (mixed in a volume ratio of 1:1) were added to the DMF layer and centrifuged at 10,000 rpm for 15 minutes. After centrifugation, the supernatant was removed, ethanol was added and centrifuged at 10,000 rpm for 15 minutes. The ethanol-centrifugation was repeated three times to obtain surface-modified upconversion nanoparticles. Step 3, preparation of dye-sensitized upconversion nanoparticles; The upconversion nanoparticles (UCNPs) prepared in step 2 were dispersed in N,N-dimethylformamide (DMF) solvent to obtain a nanoparticle suspension with a concentration of 1 mg / mL. IR806 dye powder was dissolved in DMF and sonicated for 10 min to fully dissolve it, obtaining a dye mother solution with a concentration of 500 μmol / L. The nanoparticle suspension was mixed with the dye mother solution at a volume ratio of 500:1, then transferred to a light-proof glass bottle and placed in a constant temperature shaker (25°C, 200 rpm) for 5 min in the dark to promote the anchoring of the dye molecules on the nanoparticle surface. Finally, dye-sensitized upconversion nanoparticles were obtained, which were sealed and stored in the dark at 4°C until use. Step 4, the dye-sensitized upconversion nanoparticles obtained in step 3 were dispersed in DMF solvent to obtain a dye-sensitized UCNPs suspension; the quencher NBA was dissolved in DMF solvent and ultrasonicated for 10 min to ensure its complete dissolution to obtain a quencher solution; the concentrations of the quencher solution were 0 mM, 50 mM, 100 mM, 150 mM, 200 mM and 250 mM respectively; Figure 2 FIG1 is a graph showing the stability of the dye-sensitized upconversion nanoparticles after adding NBA in Example 1. It is found that the stability is best when the concentration of the quencher solution is 150 mM.

[0024] Through the stability diagram of dye-sensitized upconversion nanoparticles after adding NBA, it was found that its stability was best at 150 mM.

[0025] The dye-sensitized UCNPs suspension was mixed with the quencher solution, and then the mixed solution was transferred to a light-proof glass bottle and placed in a constant temperature shaker. It was shaken in the dark at a temperature of 25°C and a speed of 200 rpm for 5 minutes to obtain stable quencher-functionalized dye-sensitized upconversion nanoparticles.

[0026] Example 2 The preparation method of the quencher-synergistically stabilized dye-sensitized upconversion nanoparticles of the present invention is specifically implemented according to the following steps: Step 1, synthesis of upconversion nanoparticles; specifically: Step 1.1, YCl3·6H2O, YbCl3·6H2O, and ErCl3·6H2O were dissolved in methanol, followed by the addition of octadecene and oleic acid, and the mixture was thoroughly mixed. The resulting mixture was ultrasonically treated for 10 minutes. The mixture was then stirred and heated at a stirring rate of 600 rpm and a heating temperature of 140°C for 25 minutes to remove methanol and water molecules, and then cooled to room temperature to form an oleic acid-coated precursor mixture. The mass ratio of YCl3·6H2O, YbCl3·6H2O, ErCl3·6H2O, octadecene, and oleic acid is 78:20:1.5:7:12; In step 1.2, a sodium hydroxide-ammonium fluoride-methanol mixture was added to the precursor mixture and stirred for 25 minutes. The precursor mixture was again stirred and heated at a stirring rate of 500 rpm, a heating temperature of 130° C., and a heating time of 25 minutes, and then cooled to room temperature again. The preparation process of the sodium hydroxide-ammonium fluoride-methanol mixture is as follows: 2.5 mmol of sodium hydroxide, 4 mmol of ammonium fluoride and 5 mL of methanol are mixed and ultrasonically dispersed to obtain a sodium hydroxide-ammonium fluoride-methanol mixture; the ultrasonic dispersion temperature is 25°C and the time is 10 minutes; In step 1.3, the precursor mixture obtained in step 1.2 was evacuated at room temperature for 15 minutes, then filled with nitrogen. This evacuation and nitrogen filling cycle was repeated three times to ensure the removal of oxygen from the system. Subsequently, the precursor mixture was heated to 300°C for 110 minutes, cooled to room temperature, and centrifuged at 10,000 rpm for 15 minutes. The resulting nanoparticles were redispersed in a 1:1 volume ratio cyclohexane / ethanol mixture. The mixture was centrifuged again at 10,000 rpm for 15 minutes. This dispersion and centrifugation cycle was repeated three times to ensure the purity of the nanoparticles. Finally, the collected nanoparticles were stored in the cyclohexane solution for subsequent use.

[0027] Step 2, performing surface modification treatment on the upconversion nanoparticles (UCNPs) obtained in step 1; specifically: The oleic acid-coated upconversion nanoparticles dispersed in cyclohexane were mixed with a 1 mg / mL solution of nitric acid tetrafluoroborate (NOBF4) in N, N-dimethylformamide in a volume ratio of 1:1. The mixture was shaken on a shaker at 200 rpm for 15 minutes to promote the extraction of UCNPs from the cyclohexane layer into the DMF layer. After standing for 30 minutes, the supernatant was aspirated and discarded. Toluene and cyclohexane (mixed in a volume ratio of 1:1) were added to the DMF layer and centrifuged at 10,000 rpm for 15 minutes. After centrifugation, the supernatant was removed, ethanol was added and centrifuged at 10,000 rpm for 15 minutes. The ethanol-centrifugation was repeated three times to obtain surface-modified upconversion nanoparticles. Step 3, preparation of dye-sensitized upconversion nanoparticles; The upconversion nanoparticles (UCNPs) prepared in step 2 were dispersed in N,N-dimethylformamide (DMF) solvent to obtain a nanoparticle suspension with a concentration of 1.5 mg / mL. IR806 dye powder was dissolved in DMF and sonicated for 10 min to fully dissolve it, obtaining a dye mother solution with a concentration of 700 μmol / L. The nanoparticle suspension was mixed with the dye mother solution at a volume ratio of 500:1, then transferred to a light-proof glass bottle and placed in a constant temperature shaker (25°C, 200 rpm) for 5 min in the dark to promote the anchoring of the dye molecules on the nanoparticle surface. Finally, dye-sensitized upconversion nanoparticles were obtained, which were sealed and stored in the dark at 4°C until use. Step 4: Disperse the dye-sensitized upconversion nanoparticles obtained in step 3 in DMF solvent to obtain a dye-sensitized UCNP suspension; dissolve the quencher Trolox in DMF solvent and sonicate for 10 minutes to ensure complete dissolution, thereby obtaining a quencher solution. The concentrations of the quencher solution are 0 mM, 20 mM, 40 mM, 100 mM, 200 mM, 300 mM, and 400 mM, respectively. Figure 3 This is a stability diagram of the dye-sensitized upconversion nanoparticles after adding Trolox in Example 2. It was found that the stability was best when the concentration of the quencher solution was 300 mM.

[0028] The dye-sensitized UCNPs suspension was mixed with the quencher solution. The mixed solution was then transferred to a light-proof glass bottle and placed in a thermostatic shaker at 25°C and 200 rpm for 5 min in the dark to obtain stable quencher-functionalized dye-sensitized upconversion nanoparticles. Example 3 The preparation method of the quencher-synergistically stabilized dye-sensitized upconversion nanoparticles of the present invention is specifically implemented according to the following steps: Step 1, synthesis of upconversion nanoparticles; specifically: Step 1.1, YCl3·6H2O, YbCl3·6H2O, and ErCl3·6H2O were dissolved in methanol, followed by the addition of octadecene and oleic acid, and the mixture was thoroughly mixed. The resulting mixture was ultrasonically treated for 15 minutes. The mixture was then stirred and heated at a stirring rate of 700 rpm and a heating temperature of 150°C for 30 minutes to remove methanol and water molecules, and then cooled to room temperature to form an oleic acid-coated precursor mixture. The mass ratio of YCl3·6H2O, YbCl3·6H2O, ErCl3·6H2O, octadecene, and oleic acid is 80:25:2:8:15; In step 1.2, a sodium hydroxide-ammonium fluoride-methanol mixture was added to the precursor mixture and stirred for 30 minutes. The precursor mixture was stirred and heated again at a stirring rate of 600 rpm, a heating temperature of 150° C., and a heating time of 30 minutes, and then cooled to room temperature again. The preparation process of the sodium hydroxide-ammonium fluoride-methanol mixture is as follows: 2.5 mmol of sodium hydroxide, 4 mmol of ammonium fluoride and 5 mL of methanol are mixed and ultrasonically dispersed to obtain a sodium hydroxide-ammonium fluoride-methanol mixture; the ultrasonic dispersion temperature is 25°C and the time is 10 minutes; In step 1.3, the precursor mixture obtained in step 1.2 was evacuated at room temperature for 20 minutes, then filled with nitrogen. This evacuation and nitrogen filling cycle was repeated three times to ensure the removal of oxygen from the system. Subsequently, the precursor mixture was heated to 310°C for 120 minutes, cooled to room temperature, and centrifuged at 10,000 rpm for 15 minutes. The resulting nanoparticles were redispersed in a 1:1 volume ratio cyclohexane / ethanol mixture. The mixture was centrifuged again at 10,000 rpm for 15 minutes. This dispersion and centrifugation cycle was repeated three times to ensure the purity of the nanoparticles. Finally, the collected nanoparticles were stored in the cyclohexane solution for subsequent use.

[0029] Step 2, performing surface modification treatment on the upconversion nanoparticles (UCNPs) obtained in step 1; specifically: The oleic acid-coated upconversion nanoparticles dispersed in cyclohexane were mixed with a 1 mg / mL solution of nitric acid tetrafluoroborate (NOBF4) in N, N-dimethylformamide at a volume ratio of 1:1. The mixture was shaken at 200 rpm on a shaker for 15 minutes to promote the extraction of UCNPs from the cyclohexane layer into the DMF layer. After standing for 40 minutes, the supernatant was aspirated and discarded. Toluene and cyclohexane (mixed at a volume ratio of 1:1) were added to the DMF layer and centrifuged at 10,000 rpm for 15 minutes. After centrifugation, the supernatant was removed, ethanol was added and centrifuged at 10,000 rpm for 15 minutes. The ethanol-centrifugation was repeated three times to obtain surface-modified upconversion nanoparticles. Step 3, preparation of dye-sensitized upconversion nanoparticles; The upconversion nanoparticles (UCNPs) prepared in step 2 were dispersed in N,N-dimethylformamide (DMF) solvent to obtain a nanoparticle suspension with a concentration of 2 mg / mL. IR806 dye powder was dissolved in DMF and sonicated for 10 min to fully dissolve it, obtaining a dye mother solution with a concentration of 1000 μmol / L. The nanoparticle suspension was mixed with the dye mother solution at a volume ratio of 500:1, then transferred to a light-proof glass bottle and placed in a constant temperature shaker (25°C, 200 rpm) for 5 min in the dark to promote the anchoring of the dye molecules on the nanoparticle surface. Finally, dye-sensitized upconversion nanoparticles were obtained, which were sealed and stored in the dark at 4°C until use. Step 4: Disperse the dye-sensitized upconversion nanoparticles obtained in step 3 in DMF solvent to obtain a dye-sensitized UCNPs suspension; dissolve the quenchers NBA and Trolox in DMF solvent and perform ultrasonic treatment for 10 min to ensure their complete dissolution, to obtain a quencher solution with a concentration of 225 mM; The dye-sensitized UCNPs suspension was mixed with the quencher solution, and then the mixed solution was transferred to a light-proof glass bottle and placed in a constant temperature shaker. It was shaken in the dark at a temperature of 25°C and a speed of 200 rpm for 5 minutes to obtain stable quencher-functionalized dye-sensitized upconversion nanoparticles.

[0030] Example 4 Different from Example 3, no quencher solution was added in step 4, and other parameters and conditions remained unchanged, thereby obtaining stable dye-sensitized upconversion nanoparticles.

[0031] Example 5 Different from Example 3, only the quencher NBA solution was added in step 4, and other parameters and conditions remained unchanged, thereby obtaining quencher-functionalized dye-sensitized upconversion nanoparticles.

[0032] Example 6 Different from Example 3, only the quencher Trolox solution was added in step 4, and other parameters and conditions remained unchanged, thereby obtaining quencher-functionalized dye-sensitized upconversion nanoparticles.

[0033] Figure 4 The stability test curves for the dye-sensitized upconversion nanoparticles obtained in Examples 3-6 show that the dye-sensitized upconversion nanoparticles with the addition of NBA and Trolox exhibit the best stability. NBA and Trolox efficiently quench the dye triplet state through a photoinduced electron transfer mechanism, reducing the system's fluorescence lifetime to 145 μs. This reduction in fluorescence lifetime indicates that the triplet energy of the IR806 molecule is rapidly dissipated, reducing reaction with oxygen and thus inhibiting photobleaching. The synergistic effect of NBA and Trolox increases the stability of the system by 5.7 times after 20 minutes of laser irradiation.

Claims

1. A method for preparing quencher-stabilized dye-sensitized upconversion nanoparticles, characterized in that: Please follow the steps below to implement it: Step 1, synthesizing upconversion nanoparticles; Step 2, mixing the upconversion nanoparticles obtained in step 1 with a solution of tetrafluoroborate in N,N-dimethylformamide, shaking, standing, and centrifuging to obtain surface-modified upconversion nanoparticles; Step 3, mixing the surface-modified upconversion nanoparticles, the dye, and the solvent, and shaking to obtain dye-sensitized upconversion nanoparticles; Step 4: mixing the dye-sensitized upconversion nanoparticles obtained in step 3, the quencher and the solvent, and shaking to obtain the quencher-synergistically stabilized dye-sensitized upconversion nanoparticles.

2. The method for preparing quencher-synergistically stabilized dye-sensitized upconversion nanoparticles according to claim 1, wherein: In the step 1, specifically: Step 1.1, YCl3·6H2O, YbCl3·6H2O, and ErCl3·6H2O are dissolved in methanol, followed by the addition of octadecene and oleic acid, mixed uniformly, and the resulting mixture is sonicated; the mixture is then stirred and heated, and cooled to room temperature to form an oleic acid-coated precursor mixture; Step 1.2, adding the sodium hydroxide-ammonium fluoride-methanol mixture to the precursor mixture and stirring for 20-30 minutes; stirring and heating the precursor mixture again at a temperature of 120-150° C. for 20-30 minutes, and then cooling it to room temperature again; Step 1.3: Evacuate the precursor mixture obtained in step 1.2 at room temperature and fill it with nitrogen. Repeat the evacuation and nitrogen filling three times to ensure that oxygen is removed from the system. Subsequently, the precursor mixture is heated at a temperature of 280-310°C for 80-120 minutes; cooled to room temperature and centrifuged, and the obtained nanoparticles are dispersed in a mixed solution of cyclohexane and ethanol, centrifuged, and the dispersion-centrifugation cycle is repeated three times. Finally, the collected nanoparticles are stored in the cyclohexane solution.

3. The method for preparing quencher-synergistically stabilized dye-sensitized upconversion nanoparticles according to claim 2, wherein: In the step 1.1, the mass ratio of YCl3·6H2O, YbCl3·6H2O, ErCl3·6H2O, octadecene and oleic acid is 70-80:15-25:1-2:6-8:10-15; the ultrasonic treatment time is 5-15 minutes; the stirring rate is 400-700 rpm, the heating temperature is 130-150°C, and the heating time is 20-30 minutes.

4. The method for preparing quencher-synergistically stabilized dye-sensitized upconversion nanoparticles according to claim 2, wherein: In step 1.2, the preparation process of the sodium hydroxide-ammonium fluoride-methanol mixed solution is as follows: sodium hydroxide, ammonium fluoride and methanol are mixed and ultrasonically dispersed to obtain the sodium hydroxide-ammonium fluoride-methanol mixed solution; the mass ratio of sodium hydroxide to ammonium fluoride is 6-8:10-15; the ultrasonic dispersion temperature is 15-30°C and the time is 10-30 minutes.

5. The method for preparing quencher-synergistically stabilized dye-sensitized upconversion nanoparticles according to claim 1, wherein: In step 2, specifically, the upconversion nanoparticles obtained in step 1 are mixed with a solution of tetrafluoroborate in N,N-dimethylformamide, shaken on a shaker, allowed to stand for 20-40 minutes, the supernatant is aspirated and discarded, toluene and cyclohexane are added to the DMF layer, centrifuged, the supernatant is removed, ethanol is added and centrifuged, and the addition of ethanol and centrifugation are repeated three times to obtain surface-modified upconversion nanoparticles.

6. The method for preparing quencher-synergistically stabilized dye-sensitized upconversion nanoparticles according to claim 1, wherein: In the step 3, specifically: The upconversion nanoparticles prepared in step 2 were dispersed in DMF to obtain a nanoparticle suspension with a concentration of 1-2 mg / mL; the IR806 dye powder was dissolved in DMF until it was fully dissolved to obtain a dye mother liquor with a concentration of 500-1000 μmol / L; the nanoparticle suspension was mixed with the dye mother liquor, and then transferred to a light-proof glass bottle and placed in a shaker for light-proof shaking to finally obtain dye-sensitized upconversion nanoparticles.

7. The method for preparing quencher-synergistically stabilized dye-sensitized upconversion nanoparticles according to claim 1, wherein: In the step 4, specifically: The dye-sensitized upconversion nanoparticles obtained in step 3 are dispersed in DMF solvent to obtain a dye-sensitized UCNPs suspension; the quencher is dissolved in DMF solvent, and after complete dissolution, a quencher solution with a concentration of 1-1000 mM is obtained; the dye-sensitized UCNPs suspension is mixed with the quencher solution, and then the mixed solution is transferred to a light-proof glass bottle and placed in a shaker for light-proof shaking to obtain quencher-synergistically stabilized dye-sensitized upconversion nanoparticles.

8. The method for preparing quencher-synergistically stabilized dye-sensitized upconversion nanoparticles according to claim 7, characterized in that: The quencher is specifically any one or two of nitrobenzyl alcohol, quinoline dimethacrylate, propyl gallate, ascorbic acid, and 2-mercaptoethanol. 9 . The upconversion nanoparticles prepared by the method for preparing quencher-synergistically stabilized dye-sensitized upconversion nanoparticles according to claim 1 .

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