Molecular self-assembly triplet-triplet annihilation photon upconversion hydrogel, preparation method and application thereof

Abstract

The application provides a kind of molecular self-assembly triplet-triplet annihilation (TTA) photonic upconversion hydrogel and its preparation method and application, select polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) F127 three-block polymer to encapsulate upconversion dye pair, form nanomicelles.Utilize three-block polymer hydrophilic section PEO and hydrophobic section PPO in aqueous solution self-assembly to form nanoparticles, hydrophilic end is exposed outside, form dense oxygen barrier shell, hydrophobic end and hydrophobic luminescent material in core, avoid being quenched by oxygen in air.Again, add aqueous solution containing upconversion nanoparticles into acrylamide aqueous solution, directly polymerize, obtain upconversion hydrogel.The strategy is not only simple operation, without complex modification to luminescent material, and does not contain volatile organic solvent, and polyacrylamide hydrogel also has good biocompatibility, so it has great application prospect in biological field.

Description

Technical Field

[0001] This application relates to the fields of organic optoelectronic materials and polymer materials technology, and more specifically, to a molecularly self-assembled triplet-triplet annihilation photon upconversion hydrogel, its preparation method, and its application. Background Technology

[0002] Photon upconversion based on triplet-triplet-annihilation (TTA) is a technique that converts long-wavelength, low-energy photons into short-wavelength, high-energy photons. It has attracted widespread attention from researchers due to its significant applications in solar cells, bioimaging, and photocatalysis. Compared with two-photon absorption upconversion and rare-earth material upconversion, triplet-triplet-annihilation upconversion has the following advantages: (1) it can use ultra-low intensity, incoherent excitation light, which is very close to the intensity of sunlight on the Earth's surface, as a light source; (2) the sensitizer has strong absorption of visible light (the molar extinction coefficient is usually higher than 10). 4 L·mol －1 ·cm －1 (3) The excitation wavelength and emission wavelength can be adjusted by selecting the energy donor and acceptor (energy level matching), and light of different long wavelength bands can be converted into high-energy light; (4) High upconversion quantum efficiency, etc.

[0003] TTA-UC typically occurs in organic solvents. To date, the most efficient TTA-UC systems have been realized in molecularly dispersed solutions because they allow for rapid diffusion of excited-state molecules, facilitating intermolecular collisions and energy transfer. However, excited triplet states are easily quenched by dissolved oxygen in organic solvents, requiring operation under strictly oxygen-deficient conditions. Furthermore, the volatility of organic solvents severely limits the application of excited triplet states. Early TTA-UC studies often used low-viscosity solutions; however, without addressing the issue of triplet quenching by molecular oxygen in these organic solvents, the overall TTA-UC efficiency decreases. Therefore, research using solid-state TTA-UC materials is essential. Chinese patent CN202110887048.9 discloses an organogel that achieves triplet annihilation photon upconversion in air. Using polyvinyl octal as a carrier, it forms a helical self-assembled structure with a photosensitizer and acceptor, achieving triplet annihilation photon upconversion in air. This organogel exhibits high transparency, does not scatter, and possesses a certain shape and mechanical strength at room temperature. It can be used as an upconversion carrier, achieving triplet annihilation photon upconversion in air and at room temperature with good repeatability and stability. However, this gel still requires the use of an organic solvent, which has drawbacks such as solvent volatility, greatly limiting its application.

[0004] Application content

[0005] The technical problem this application aims to solve is overcoming the difficulty of using organic solvents in existing upconversion gel carriers. It provides a molecularly self-assembled triplet-tritt annihilation photon upconversion hydrogel. Through molecular self-assembly, utilizing the hydrophilic-hydrophobic interactions of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)F127 triblock polymer, at low concentrations, the hydrophilic PEO portion remains in an swollen state while the hydrophobic PPO portion remains in a contracted state. The resulting hydrophobic core can accommodate lipophilic guests, thereby achieving highly efficient triplet annihilation upconversion emission under air conditions. Acrylamide can be used as an upconversion carrier, which is not only simple to operate without complex modification of the luminescent material, but also free of volatile organic solvents. Furthermore, polyacrylamide hydrogels have good biocompatibility, making them promising for applications in the biological field.

[0006] Another objective of this application is to provide a method for preparing a molecularly self-assembled triplet-triplet annihilation photon upconversion hydrogel.

[0007] The above-mentioned objectives of this application are achieved through the following technical solutions:

[0008] A self-assembled triplet-trip annihilation photon upconversion hydrogel, through molecular self-assembly and utilizing the hydrophilic-hydrophobic interaction of F127, exhibits a hydrophilic PEO moiety that remains swollen while the hydrophobic PPO moiety remains contracted at low concentrations. The resulting hydrophobic core can accommodate lipophilic guests, thus achieving highly efficient triplet annihilation upconversion emission under air conditions. Acrylamide, containing carbon-carbon double bonds and amide groups, exhibits the general chemical property of double bonds: it readily polymerizes to form a hydrogel under ultraviolet irradiation or at its melting point. Using acrylamide as a monomer, an organogel capable of triplet annihilation photon upconversion was prepared by self-assembly with a porphyrin-based photosensitizer and acceptor. The molar ratio of the porphyrin-based photosensitizer, acceptor, acrylamide, initiator, crosslinking agent, and catalyst was 67–150:6700–15000:37600–84600:26–60:45–180:8907–20040, and the mass ratio of F127 to the upconversion micelle solution was 1:0.07–0.15.

[0009] Preferably, in step S1, the molar ratio of octaethylporphyrin platinum to 9,10-diphenylanthracene is 1-2:150-300. More preferably, in step S1, the molar ratio of octaethylporphyrin platinum to 9,10-diphenylanthracene is 1:150.

[0010] Preferably, the solvent for the reaction in step S1 is tetrahydrofuran (THF) and methanol.

[0011] Preferably, the reaction temperature in step S1 is 50–75°C and the reaction time is 1–2 h; more preferably, the reaction temperature is 60°C and the reaction time is 1 h.

[0012] Preferably, the ratio of upconversion dye to F127 in step S2 is 1-2:0.1-0.2. More preferably, the mass ratio of upconversion dye to F127 in step S2 is 1:0.1.

[0013] Preferably, the solvent for the reaction in step S2 is tetrahydrofuran (THF) and methanol.

[0014] Preferably, the reaction temperature in step S2 is 50–75°C and the reaction time is 1–2 h; more preferably, the reaction temperature is 60°C and the reaction time is 1 h.

[0015] Preferably, the treatment in step S2 involves rotary evaporation under reduced pressure at a temperature of 50–75°C for 0.5–1 h to remove the organic solvent. More preferably, the treatment in step S2 involves rotary evaporation under reduced pressure at a temperature of 60°C for 0.5 h to remove the organic solvent.

[0016] Preferably, in step S3, the distilled water needs to be preheated and slowly added to the upconversion polymer film.

[0017] More preferably, the distilled water in step S3 needs to be preheated to 60°C.

[0018] Preferably, the reaction temperature in step S3 is 50–75°C and the reaction time is 0.5–1 h; more preferably, the reaction temperature is 60°C and the reaction time is 0.5 h.

[0019] Preferably, the rotational speed in step S3 should be 50–150 r / min. More preferably, the rotational speed in step S3 should be 100 r / min.

[0020] Preferably, the reaction conditions in step S3 are such that after complete hydration and the absence of a solid film in the bottle, a clear pink upconversion micelle solution can be obtained by filtration using a 0.45 μm aqueous filter.

[0021] Preferably, in step S4, 0.5 ml of upconversion micelle solution is used, wherein the molar ratio of Ptoep, DPA, and acrylamide is 67–150:6700–15000:37600–84600, to obtain a prepolymerized upconversion micelle solution. More preferably, in step S4, the molar ratio of Ptoep, DPA, and acrylamide is 1:100:564.

[0022] Preferably, in step S5, the molar ratio of Ptoep, DPA, and acrylamide to BIS, KPS, and TEMED in the prepolymerized upconversion micelle solution is 67–150:6700–15000:37600–84600:26–60:45–180:8907–20040. More preferably, in step S5, the molar ratio of Ptoep, DPA, and acrylamide to BIS, KPS, and TEMED in the prepolymerized upconversion micelle solution is 100:10000:56400:39:90:13360.

[0023] Preferably, in step S5, the upconversion hydrogel should be allowed to stand for 0–60 minutes to allow it to completely solidify. More preferably, in step S5, the upconversion hydrogel should be allowed to stand for 30 minutes to allow it to completely solidify.

[0024] The molecularly self-assembled triplet annihilation photon upconversion hydrogel prepared by the method described above is also within the scope of protection of this application.

[0025] Meanwhile, the preparation process of the compound described in this application is simple, convenient, and can be prepared in large-scale batches, which is conducive to industrial production and the promotion of its application. Attached Figure Description

[0026] Figure 1 This describes the preparation method of the molecular self-assembled triplet annihilation photon upconversion hydrogel obtained in Example 1.

[0027] Figure 2 This is a photograph of the upconversion blue light emission of the molecularly self-assembled triplet annihilation photon upconversion micelle aqueous solution prepared in Example 1 after being excited by green light in an air environment.

[0028] Figure 3 (a) Absorption diagrams of the acceptor DPA and photosensitizer octyl porphyrin platinum in the molecularly self-assembled triplet annihilation photon upconversion micelles prepared in Example 1 in F127 micelle aqueous solution and deoxygenated THF; (b) Emission diagrams of the acceptor 9,10-diphenylanthracene (DPA) and photosensitizer octyl porphyrin platinum (PtOEP) in the prepared molecularly self-assembled triplet annihilation photon upconversion micelles in F127 micelle aqueous solution and deoxygenated tetrahydrofuran (THF). The excitation wavelength was 532 nm.

[0029] Figure 4 Absorption and emission spectra of F127 upconversion micelles loaded with (a) DPA and (b) PtOEP embedded in polyacrylamide (PAAM) hydrogel.

[0030] Figure 5(a) Photoluminescence spectra of PAAM upconversion hydrogel under different power 532 nm light excitation under air conditions; (b) Dependence of upconversion emission integral on incident power density, with slopes of the corresponding lines being 2.03 and 0.92, respectively; (c) Quantum yield of upconversion hydrogel at room temperature.

[0031] Figure 6 The upconversion emission spectrum of PAAM upconversion hydrogel under air conditions was obtained by continuous excitation with a 532 nm laser.

[0032] Figure 7 (a), (b), and (c) are cross-sectional scanning electron microscope images of PAAM hydrogel, and (d), (e), and (f) are cross-sectional scanning electron microscope images of PAAM-UCNPs hydrogel.

[0033] Figure 8 (a) A diagram illustrating the mechanism of upconversion in biological applications, showing how upconverted emitted light is guided to the target area via optical fiber, thereby reducing light loss at the skin and damage to the skin. (b) A diagram of total internal reflection from an upconversion fiber. (c) Using an upconversion fiber to guide green light into the body through the skin layer of pork and convert it into blue light.

[0034] Figure 9 This is a schematic diagram of the PAAM upconversion hydrogel mechanism. Detailed Implementation

[0035] The present application will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present application and are not intended to limit the scope of the present application. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0036] The applicant's research revealed that water-soluble polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO-PPO-PEO) triblock copolymers are an important class of amphiphilic molecules, commercially known as Pluronics, also called poloxamers. These are nonionic surfactant triblock copolymers with different molecular weights that spontaneously form multi-molecular aggregates of micelles in aqueous solutions. Their core is primarily composed of hydrophobic PPO blocks, doped with several PEO blocks, with the remaining PEO blocks surrounding the outer shell. This micelle structure disperses well in aqueous solutions, and the PPO-dominant core provides a locally hydrophobic microenvironment in the aqueous phase, thus solubilizing oil-soluble compounds. In an aqueous environment, F127 can uniquely self-assemble into micelles of approximately 30 nm. At low concentrations, its hydrophilic PEO portion remains swollen, while the hydrophobic PPO portion remains contracted. The formed hydrophobic core can accommodate lipophilic guests, and at concentrations of 20% or higher, it exhibits ideal reversible gel properties with temperature changes. However, F127 gel is formed by the accumulation and entanglement of micelles when a certain temperature and concentration are reached. Therefore, this gel is very sensitive to temperature, has poor mechanical properties, and is not processable. Acrylamide, on the other hand, contains carbon-carbon double bonds and amide groups, exhibiting the general chemical properties of double bonds: under ultraviolet irradiation or at its melting point, it readily polymerizes to form hydrogels with better biocompatibility and processability.

[0037] This application provides a molecularly self-assembled triplet-triplet annihilation photon upconversion hydrogel, characterized in that it comprises an acrylamide monomer, a porphyrin photosensitizer, an acceptor, a crosslinking agent, an initiator, and a catalyst, wherein the molar ratio of the porphyrin photosensitizer, acceptor, acrylamide monomer, crosslinking agent, initiator, and catalyst is (50-200):(5000-20000):(28200-112800):(20-80):(60-135):(6680-26720).

[0038] This hydrogel, through molecular self-assembly and utilizing the hydrophilic-hydrophobic interaction of F127, exhibits a hydrophilic PEO moiety that remains swollen while the hydrophobic PPO moiety remains contracted at low concentrations. The resulting hydrophobic core can accommodate lipophilic guests, thus achieving highly efficient triplet annihilation upconversion emission under air conditions. Acrylamide can serve as an upconversion carrier, offering advantages such as simple operation, no need for complex modification of the luminescent material, and absence of volatile organic solvents. Furthermore, polyacrylamide hydrogels possess excellent biocompatibility, making them promising candidates for applications in the biological field.

[0039] In some embodiments, the molar ratio of the porphyrin photosensitizer, receptor, acrylamide, crosslinking agent, initiator, and catalyst is (67-150):(6700-15000):(37600-84600):(26-60):(45-180):(8907-20040).

[0040] In some preferred embodiments, the porphyrin photosensitizer is one or more of octaethylporphyrin platinum, tetraphenylporphyrin platinum, and planar tris(2-phenylpyridyl-N,C2')iridium(III).

[0041] In some preferred embodiments, the receptor is one or more of 9,10-diphenylanthracene, perylene, and pyrene.

[0042] This application also provides a method for preparing the above-mentioned molecular self-assembled triplet-triplet annihilation photon upconversion hydrogel, characterized by comprising the following steps:

[0043] S1. An upconversion dye was prepared by mixing octaethylporphyrin platinum, 9,10-diphenylanthracene, tetrahydrofuran, and methanol.

[0044] S2. The upconversion dye obtained in S1 is mixed with F127 and reacted to obtain an upconversion polymer;

[0045] S3. The upconversion polymer obtained in S2 is mixed with water and reacted to obtain an upconversion micelle solution;

[0046] S4. Mix the upconversion micelle solution obtained in S3 with acrylamide to obtain an upconversion solution;

[0047] S5. Add crosslinking agent N,N-methylenebisacrylamide, initiator potassium persulfate, and catalyst N,N,N',N'-tetramethylethylenediamine to the upconversion solution prepared in S4, and react to prepare a hydrogel, thus obtaining the target product.

[0048] In some preferred embodiments, the molar ratio of octaethylporphyrin platinum and 9,10-diphenylanthracene in step S1 is (1-2):(150-300); the reaction temperature is 50-75°C; and the reaction time is 1-2 h.

[0049] In some preferred embodiments, the reaction temperature in step S2 is 50–75°C; the reaction time is 1–2 h; and the mass ratio of upconversion dye to F127 is (1–2):(0.1–0.2).

[0050] In some preferred embodiments, the temperature of the reaction in step S3 is 50–75°C; the reaction time is 0.5–1 h.

[0051] In some preferred embodiments, in step S4, 0.5 ml of upconversion micelle solution is prepared, wherein the molar ratio of octaethylporphyrin platinum, 9,10-diphenylanthracene and acrylamide is (67-150):(6700-15000):(37600-84600), to obtain a prepolymerized upconversion micelle solution.

[0052] In some preferred embodiments, the prepolymerized upconversion micelle solution in step S5, wherein the content of octaethylporphyrin platinum, 9,10-diphenylanthracene, and acrylamide is in the molar ratio of N,N-methylenebisacrylamide, potassium persulfate, and N,N,N',N'-tetramethylethylenediamine as (67-150):(6700-15000):(37600-84600):(26-60):(45-180):(8907-20040), and the reaction time is 0-1 h, yields a pink transparent polyacrylamide upconversion hydrogel.

[0053] This application also provides the application of the above-mentioned molecularly self-assembled triplet-triplet annihilation photon upconversion hydrogel in photoluminescent devices.

[0054] The preparation method of the molecular self-assembled triplet-triplet annihilation photon upconversion hydrogel in this application will be described in detail below.

[0055] Example 1

[0056] 0.0033 g of 9,10-diphenylanthracene (DPA) and 100 μL of 1 mmol / L octaethylporphyrin platinum (PtOEP) upconversion dye in toluene were weighed into a round-bottom flask. Appropriate amounts of tetrahydrofuran (THF) and methanol were added, and the mixture was heated in an oil bath at 60 °C for 1 h to dissolve. While still hot, 1 g of the polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO)F127 triblock polymer was added to the round-bottom flask, and the mixture was heated again in an oil bath at 60 °C for 1 h to dissolve. Then, the mixture was rotary evaporated under reduced pressure at 60 °C for 30 min to remove the organic solvents tetrahydrofuran and methanol, yielding an upconversion polymer film. Add an appropriate amount of preheated distilled water (60°C) to the obtained upconversion polymer film, stir in an oil bath at 60°C for more than 30 minutes at a speed of 100 r / min, until hydration is complete and there is no solid film in the bottle, then filter with a 0.45 μm aqueous filter to obtain a clear pink upconversion micelle solution.

[0057] Take 100 mg of N,N-methylenebisacrylamide (BIS) and 250 mg of potassium persulfate (KPS) in small glass bottles, and add 5.0 mL of deionized water to each (BIS solution concentration 0.013 mol / L, KPS solution concentration 0.018 mol / L). Take 0.2 g of acrylamide monomer in a small glass bottle, add 1.0 mL of deionized water, and stir well. Add 15 μL of BIS solution, 25 μL of KPS solution, 0.5 mL of the above-prepared nanomicelle aqueous solution, and then add 10 μL of N,N,N',N'-tetramethylethylenediamine (TEMED). Stir rapidly to mix the solution thoroughly. Pour the liquid into a polytetrafluoroethylene mold and an optical cuvette, and after standing for 30 min, a pink transparent polyacrylamide upconversion hydrogel is obtained.

[0058] Characterization and performance testing

[0059] Using the molecular self-assembled gel prepared in Example 1 as the test object, its photophysical properties and performance were tested, and the test results are as follows: Figures 2 to 8 As shown.

[0060] Figure 1 This is a flowchart illustrating the preparation of a self-assembled triplet annihilation photon upconversion hydrogel. N,N-methylenebisacrylamide (BIS) and potassium persulfate (KPS) were placed in small glass bottles, and deionized water was added to each. Acrylamide monomer was placed in a small glass bottle, deionized water was added, and the mixture was stirred until homogeneous. The BIS solution, KPS solution, and the prepared nanomicelle aqueous solution were added, followed by N,N,N',N'-tetramethylethylenediamine (TEMED). The mixture was stirred rapidly until homogeneous. The liquid was injected into a polytetrafluoroethylene mold and an optical cuvette, and allowed to stand to obtain a pink, transparent polyacrylamide upconversion hydrogel.

[0061] Figure 2 This is an image showing the upconversion blue light emission of aqueous upconversion dye micelles after being excited by green light in air following molecular self-assembly triplet annihilation photons. When excited with 532 nm excitation light, the upconversion dye micelle aqueous solution, visible to the naked eye, can produce the same upconversion emission as measured in the deoxygenated solvent THF, even without deoxygenation.

[0062] Figure 3(a) Absorption spectrum of self-assembled triplet annihilation photon upconversion micelles measured by a Shimadzu UV-2700 UV-Vis spectrophotometer. The absorption spectra of aqueous upconversion micelles loaded with PtOEP and DPA were measured and compared with the absorption spectra of PtOEP / DPA in the deoxygenated organic solvent THF. When the same concentration of dye was used in the micelle solution, the absorbance of the upconversion dye pair decreased compared with that in the organic solvent THF, and the characteristic structure of the absorption peak of the acceptor DPA disappeared. This is because the high concentration of aggregated acceptors within the micelles formed larger aggregates that do not absorb light. (b) Emission spectrum of self-assembled triplet annihilation photon upconversion micelles obtained by a marine optical multi-functional spectrometer at an excitation wavelength of 532 nm. When excited by 532 nm excitation light, the upconversion dye micelle aqueous solution can produce upconversion emission as measured in the deoxygenated solvent THF without deoxygenation. These results indicate that the nanomicelles formed by F127 self-assembly can serve as a matrix for achieving effective TTA upconversion in an air environment.

[0063] Figure 4 Absorption spectra of self-assembled triplet annihilation photon upconversion micelles obtained by a Shimadzu UV-2700 UV-Vis spectrophotometer. Aqueous solutions of F127 nanomicelles loaded only with DPA and immobilized in hydrogels were tested. The absorption spectrum showed four distinct peaks (339 nm, 356 nm, 375 nm, 385 nm) and one weak peak (323 nm). The emission spectrum showed a broad emission range of 394 nm-532 nm, similar to the absorption and emission spectra of DPA in the THF (Thyristor Fiber Optic) range. Figure 4 (a) and PtOEP loaded only in PAAM hydrogel showed two sharp absorption peaks at 381 nm (Soret absorption band) and 535 nm (Q band), and a sharp phosphorescence emission peak concentrated at 645 nm. Figure 4 (b) Solutions containing PtOEP exhibit the same spectral characteristics as THF. DPA shows the same emission behavior in THF. In summary, the immobilization of the hydrogel has almost no effect on the absorption and emission of the upconversion dye within it.

[0064] Figure 5 This image shows the emission spectrum of a self-assembled triplet annihilation photon upconversion hydrogel obtained by a marine optical multi-functional spectrometer at an excitation wavelength of 532 nm. The emission spectrum clearly shows the upconversion emission of the DPA at 434 nm. The excitation threshold is an important parameter for evaluating the TTA-UC process. The PAAM upconversion hydrogel receives excitation light at 532 nm. By adjusting the intensity of the incident light, the upconversion power dependence of this system was measured, starting from 3.0 mW·cm⁻¹. -2 Low power excitation up to 300mW·cm -2 High power excitation ( Figure 5 (a)) yielded an excitation threshold of 15.2 mW·cm. -2 ( Figure 5 (b) As the incident light power increases, the upconversion emission intensity increases, reaching 100 mW·cm⁻¹. -2 At that time, the quantum yield reached its maximum of 10.8%, such as Figure 5 As shown in (c).

[0065] Figure 6 To improve the air stability of the upconversion hydrogel, continuous high-intensity excitation light (500 mW·cm⁻¹) was used. -2 The PAAM upconversion hydrogel was subjected to prolonged excitation to test its stability under air conditions, including continuous irradiation for 80 minutes. Although dissolved oxygen molecules quenched some of the triplet excitons on the micelle surface, causing a slight decrease in UC emission intensity compared to the initial test, the emission intensity remained above 85% after 80 minutes of high-intensity excitation light irradiation. This is because the packaging polymer chains tightly encapsulate the micelle core, preventing oxygen from easily diffusing into the micelles. Furthermore, the PAAM hydrogel provides support and protection within the micelles, and its intricate network of pores also effectively blocks oxygen ingress. Therefore, this indicates that the micelle and hydrogel structure provides excellent oxygen barrier and protection for the internal dye pair, thus maintaining the stability of the upconversion effect and air resistance.

[0066] Figure 7 These are scanning electron microscope (SEM) images of the cross-sections of hydrogels. Pure upconversion hydrogels without and containing nanomicelles were freeze-dried to preserve their original morphology. They were then frozen and fractured using liquid nitrogen, and their cross-sectional structures were directly imaged using a scanning electron microscope. The images are derived from the micrographs. Figure 7 In (a, b, c), it can be seen that the hydrogel without upconversion nanomicelles has a smooth porous network structure in cross-section, while the hydrogel containing nanomicelles has many particles loaded on the surface of its internal cavity, such as... Figure 7 (d, e, f), therefore, it is these complex structures that provide space for the existence of nanomicelles and have the effect of isolating oxygen.

[0067] Figure 8 This demonstrates the application of this gel in the biological field. Utilizing the high transparency and non-toxicity of PAAM upconversion hydrogel, it was fabricated into fiber-sized pieces, inserted into the skin, and delivered to the lesion site. (a) Schematic diagram of the mechanism of upconversion in the biological field: upconverted emitted light is guided to the target site via optical fiber, thereby reducing light loss at the skin's edge and its impact on the skin. (b) Total internal reflection diagram of upconversion optical fiber. (c) Using upconversion optical fiber to guide green light into the body through the skin layer of pork and convert it into blue light.

[0068] Figure 9 This is a schematic diagram of the PAAM upconversion hydrogel mechanism. Figure 9 As can be seen, the upconversion dye pair was encapsulated using a triblock polymer of polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO)F127 to form nanomicelles. The hydrophilic segment PEO and the hydrophobic segment PPO of the triblock polymer self-assembled in an aqueous solution to form nanoparticles. The hydrophilic end was exposed, forming a dense oxygen-barrier shell, while the hydrophobic end and the hydrophobic luminescent material were located at the core, preventing quenching by atmospheric oxygen. The aqueous solution containing the upconversion nanoparticles was then added to an acrylamide aqueous solution for direct polymerization, yielding an upconversion hydrogel.

[0069] This application provides a molecularly self-assembled triplet-triplet annihilation (TTA) photonic upconversion hydrogel, its preparation method, and its applications. An upconversion dye pair is encapsulated using a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)F127 triblock polymer to form nanomicelles. The hydrophilic segment PEO and the hydrophobic segment PPO of the triblock polymer self-assemble in an aqueous solution to form nanoparticles. The hydrophilic ends are exposed, forming a dense oxygen-barrier shell, while the hydrophobic ends and the hydrophobic luminescent material are located at the core, preventing quenching by atmospheric oxygen. The aqueous solution containing the upconversion nanoparticles is then added to an acrylamide aqueous solution for direct polymerization to obtain the upconversion hydrogel. This strategy is not only simple to operate, requiring no complex modification of the luminescent material, but also free of volatile organic solvents. Furthermore, the polyacrylamide hydrogel exhibits good biocompatibility, thus showing great promise for applications in the biological field.

[0070] Obviously, the above embodiments of this application are merely examples for clear illustration and are not intended to limit the implementation of this application. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of the claims of this application.

Claims

1. A molecularly self-assembled triplet-triplet annihilation photon upconversion hydrogel, characterized in that, The product comprises acrylamide monomer, porphyrin photosensitizer, acceptor, crosslinking agent, initiator, and catalyst, wherein the molar ratio of the porphyrin photosensitizer, acceptor, acrylamide monomer, crosslinking agent, initiator, and catalyst is (50~200):(5000~20000):(28200~112800):(20~80):(60~135):(6680~26720). The hydrogel is prepared by copolymerizing upconversion dye with F127 triblock polymer to form nanomicelles and copolymerizing with acrylamide monomer.

2. The molecular self-assembled triplet-triplet annihilation photon upconversion hydrogel according to claim 1, characterized in that, The porphyrin photosensitizer is one or more of octaethylporphyrin platinum and tetraphenylporphyrin platinum.

3. The molecular self-assembled triplet-triplet annihilation photon upconversion hydrogel according to claim 1, characterized in that, The receptor is one or more of 9,10-diphenylanthracene, perylene, and pyrene.

4. The method for preparing the molecular self-assembled triplet-triplet annihilation photon upconversion hydrogel according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1. An upconversion dye was prepared by mixing octaethylporphyrin platinum, 9,10-diphenylanthracene, tetrahydrofuran, and methanol. S2. The upconversion dye obtained in S1 is mixed with F127 and reacted to obtain an upconversion polymer, wherein the mass ratio of F127 to upconversion dye is 1:0.1-0.2; S3. The upconversion polymer obtained in S2 is mixed with water and reacted to obtain an upconversion micelle solution; S4. The upconversion micelle solution obtained in S3 is mixed with acrylamide to obtain an upconversion solution; S5. Add crosslinking agent N,N-methylenebisacrylamide, initiator potassium persulfate, and catalyst N,N,N',N'-tetramethylethylenediamine to the upconversion solution obtained in S4. Let the polymerization reaction stand for 0-60 minutes to obtain a hydrogel, and the target product can be obtained.

5. The method for preparing the molecular self-assembled triplet-triplet annihilation photon upconversion hydrogel according to claim 4, characterized in that, In step S1, the molar ratio of octaethylporphyrin platinum to 9,10-diphenylanthracene is (1~2): (150~300); the reaction temperature is 50~75 ℃; and the reaction time is 1~2 h.

6. The method for preparing the molecular self-assembled triplet-triplet annihilation photon upconversion hydrogel according to claim 4, characterized in that, The reaction temperature in step S2 is 50~75 ℃; the reaction time is 1~2 h; and the mass ratio of upconversion dye to F127 is (1~2): (0.1~0.2).

7. The method for preparing the molecular self-assembled triplet-triplet annihilation photon upconversion hydrogel according to claim 4, characterized in that, The reaction temperature in step S3 is 50~75 ℃; the reaction time is 0.5~1 h.

8. The method for preparing the molecular self-assembled triplet-triplet annihilation photon upconversion hydrogel according to claim 4, characterized in that, In step S4, 0.5 ml of upconversion micelle solution is prepared, wherein the molar ratio of octaethylporphyrin platinum, 9,10-diphenylanthracene, and acrylamide is (67~150):(6700~15000):(37600~84600), to obtain a prepolymerized upconversion micelle solution; and / or In step S5, the prepolymerized upconversion micelle solution contains octaethylporphyrin platinum, 9,10-diphenylanthracene, and acrylamide in a molar ratio of (67~150):(6700~15000):(37600~84600):(26~60):(45~180):(8907~20040) with a reaction time of 0~1 h, yielding a pink transparent polyacrylamide upconversion hydrogel.

9. The application of the molecular self-assembled triplet-triplet annihilation photon upconversion hydrogel according to any one of claims 1 to 3 in photoluminescent devices.

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