A near-infrared light excited covalent organic framework photosensitizer and a preparation method and application thereof

Abstract

The application discloses a kind of near-infrared light excited covalent organic framework photosensitizer and its preparation method and application, it is related to photosensitive material and photodynamic therapy technical field.The photosensitizer is constructed into nanoscale covalent organic framework structure by periodic topological crosslinking from near-infrared absorption unit, and the active oxygen generation efficiency is significantly improved by conformational constraint.Under the irradiation of 808 nm laser, the active oxygen yield of near-infrared excited high-crystalline organic photosensitizer is about 7 times higher than monomer, and shows I / II type double-channel photosensitive characteristics.The material overcomes the problem that the photosensitive efficiency is limited by the disordered accumulation of traditional small-molecule photosensitizer, and verifies the imaging-guided photodynamic therapy effect in melanoma mouse model.The photosensitizer has the advantages of deep activation, high stability and high photosensitive efficiency.

Description

Technical Field

[0001] This invention relates to the field of photosensitive materials and photodynamic therapy technology, and more specifically, to a near-infrared light-excited covalent organic framework photosensitizer, its preparation method, and its application. Background Technology

[0002] The effectiveness of deep tumor treatment largely depends on precise localization of the lesion and selective ablation capabilities. Photodynamic therapy (PDT) is considered an important tumor treatment method due to its advantages such as real-time visualization, in-situ treatment, and minimal invasiveness. However, most photosensitizers currently used in clinical practice rely on visible light excitation, resulting in limited tissue penetration depth, which is insufficient to meet the treatment needs of deep tumors, especially highly invasive and drug-resistant tumors such as melanoma. Furthermore, the prevalent gene mutations and drug resistance mechanisms in tumor cells severely affect the efficacy of traditional treatment methods, making the development of efficient, safe, and deep-excitation photosensitizers of great significance.

[0003] In recent years, organic photosensitizers with aggregation-induced emission (AIE) properties have attracted attention due to their potential to suppress non-radiative decay, improve photostability, and enhance reactive oxygen species (ROS) generation. However, existing AIE photosensitizers are usually in small molecule form, which easily forms disordered aggregates in the biological environment, leading to increased energy dissipation and decreased ROS generation efficiency. Furthermore, these molecules structurally rely on strong D–A interactions to achieve near-infrared absorption, but the resulting enhanced hydrophobicity and irregular stacking often further exacerbate photobleaching and quenching effects. Although some studies have attempted to improve molecular arrangement through crystal engineering or self-assembly strategies, these efforts are often limited by insufficient crystallinity or the excitation wavelength remaining in the near-infrared short-wavelength region (~700 nm), making it difficult to fully utilize the excellent penetration performance of the 808 nm light source.

[0004] To enhance photosensitivity, constructing covalent organic frameworks (COFs) with periodically ordered structures has become a promising strategy. COFs, through their high crystallinity and topological constraints, can effectively modulate the spatial conformation of photosensitive units, potentially enhancing intersystem crossing efficiency and increasing reactive oxygen species (ROS) yield. However, most existing COF photosensitizers rely on visible light excitation, and there is a lack of COF materials capable of efficient response at 808 nm wavelength. Furthermore, the correlation between conformational confinement and photosensitivity efficiency in COF structures remains poorly understood, limiting the further development of this type of material towards photodynamic therapy for deep tumors.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a near-infrared light-excited covalent organic framework photosensitizer, its preparation method, and its application. The photosensitizer maintains a high efficiency in generating reactive oxygen species (ROS) in a nanocrystalline state and under 808 nm excitation light, overcoming the bottlenecks caused by the disordered aggregation and insufficient near-infrared excitation efficiency of traditional small molecule photosensitizers. At the same time, it allows the release of NIR-II fluorescence signals when excited by 808 nm excitation light, increasing the tissue penetration depth and realizing precise photodynamic therapy of deep tumors under NIR-II fluorescence guidance.

[0007] This invention is implemented as follows: In a first aspect, the present invention provides a near-infrared light-excited covalent organic framework photosensitizer, the general structural formula of which is shown in formula (I):

[0008] R1 is selected from S, Se or elements in the same group; R2 is selected from branched or straight-chain alkyl groups.

[0009] In an optional embodiment, the photosensitizer generates reactive oxygen species under irradiation with a laser at a wavelength of 808 nm, and simultaneously generates singlet oxygen and superoxide anions, thus being a type I / II mixed photosensitizer.

[0010] Secondly, the present invention provides a method for preparing a near-infrared light-excited covalent organic framework photosensitizer, comprising the following steps: preparing a first compound containing a dialdehyde group; and coupling the first compound and a second compound via a palladium (Pd) catalyst to prepare a DAD-type aldehyde monomer. mBBT The aldehyde monomer and the amine linking unit are mixed and subjected to an imine condensation reaction under solvothermal conditions to generate... mBBT COF, along with the addition of polyvinylpyrrolidone for nano-sizing, yields a covalent organic framework photosensitizer. mBBT n COF.

[0011] In an optional embodiment, the DAD-type aldehyde monomer includes a benzothiadiazole (BBT) or benzoselenide diazole acceptor, a triphenylamine (TPA) donor, and an alkyl-modified thiophene conjugated unit.

[0012] In an optional embodiment, the amino linker includes p-phenylenediamine (PDA) or 2,3,5,6-tetraamino-1,4-benzoquinone (TABQ).

[0013] In an optional embodiment, the preparation method of the first compound includes: reacting 4,4'-((4-bromophenyl)azonyl)dibenzaldehyde and pinacol diboronic acid under a palladium catalyst and a vacuum condition with stirring, and then purifying the compound by column chromatography after the reaction is completed; And / or, the second compound is a dibromodithiophene benzobis(selen) diazole derivative.

[0014] In an optional embodiment, the coupling reaction is carried out under palladium catalyst catalysis and an inert gas atmosphere: the first compound and the second compound are dissolved in an organic solvent, heated to react, and then purified by extraction, drying, and column chromatography.

[0015] In an optional embodiment, the nanoforming process includes: mixing an aldehyde monomer, an amine linker and polyvinylpyrrolidone (PVP), reacting them under high-energy ultrasonic conditions, and then resuspending and dispersing them in a buffer solution.

[0016] Thirdly, the present invention provides the application of a near-infrared light-excited covalent organic framework photosensitizer in the preparation of a drug for intracellular or in vivo near-infrared II imaging and photodynamic therapy.

[0017] In an optional implementation, the drug is used to treat melanoma or other deep solid tumors.

[0018] The present invention has the following beneficial effects: (1) The highly crystalline photosensitizer proposed in this invention achieves the orderly arrangement of photosensitizing units through the inherent periodic topological constraint of COF, significantly suppresses non-radiative decay and improves intersystem crossing efficiency, thereby still being able to efficiently generate reactive oxygen species in the aggregated state and improve the efficacy of photodynamic therapy.

[0019] (2) The highly crystalline photosensitizer proposed in this invention possesses near-infrared II fluorescence emission characteristics, significantly enhancing tissue penetration depth and enabling real-time imaging and treatment of deep tumors. Nanoscale form mBBT nCOF exhibits good dispersibility and stability, meeting the requirements for in vivo applications. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Picture 1 In this invention mBBT A schematic diagram of the synthesis; Picture 2 In this invention mBBT Absorption and fluorescence emission spectra of [the substance] in THF; Picture 3 In this invention mBBT Built with PDA mBBT -Schematic diagram of COF structure; Picture 4 In this invention mBBT - Experimental and simulated PXRD diffraction patterns of COF; Picture 5 For those having the corresponding lattice spacing in this invention mBBT -COF transmission electron microscope image; Picture 6 In the PBS solution of this invention mBBT - n Transmission electron microscope image of COF; Picture 7 In this invention mBBT - n Particle size distribution of COF in PBS solution; Picture 8 In this invention mBBT - n Absorption and fluorescence emission spectra of COF in PBS (10 μg / mL); Picture 9 DCFH (10 μM) in this invention mBBT and mBBT - n Fluorescence spectral changes of COF (10 μg / mL) under 808 nm laser irradiation; Picture 10 For the present invention mBBT - n Changes in intracellular reactive oxygen species levels in COF-treated (10 μg / mL) and untreated B16F10 cells after irradiation at 808 nm (0.5 W / cm², 10 min) for 6 h. Picture 11 The B16F10 cells in this invention are used in the presence or absence of mBBT - n Cell viability assay under COF (10 μg / mL) and 808 nm irradiation conditions (0.5 W / cm², 10 min); Picture 12 Annexin V-FITC / PI flow cytometry analysis of B16F10 cells in this invention; Picture 13 For intravenous injection in this invention mBBT - nNear-infrared 2D angiography after COF (200 μg / mL); Picture 14 In this invention mBBT - n Ex vivo near-infrared 2-zone fluorescence images of major organs and their corresponding bright-field photographs 60 h after COF intravenous injection. Picture 15 For the tumor in this invention, during injection mBBT n NIR at 0 min and 30 min after COF (1 mg / mL) II imaging; Picture 16 For evaluation in this invention mBBT - n COF in vivo photodynamic therapy efficacy. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0023] The following is a detailed description of a highly crystalline COF photosensitizer proposed in this application, its preparation method, and its application.

[0024] Traditional organic photosensitizers that can be excited by near-infrared light generally suffer from technical bottlenecks such as low photosensitivity efficiency in aggregated states, limited reactive oxygen species generation, and unsatisfactory therapeutic effects in deep tissues. Although aggregation-induced emission (AIE) strategies have improved photosensitivity to some extent, small molecule photosensitizers are prone to forming disordered aggregates in the biological environment, and the uncontrollable molecular arrangement leads to low photosensitivity efficiency. Furthermore, it is difficult to fully utilize the advantages of 808nm excitation light in terms of tissue penetration and biocompatibility.

[0025] Based on the shortcomings of existing photosensitizers, this invention innovatively proposes a highly crystalline covalent organic framework (COF) photosensitizer that can be excited at 808 nm. mBBT COF. This involves using D-A-D type monomers with near-infrared photosensitivity. mBBT By introducing a COF mesh framework, the periodic topology of COF is used to constrain the conformation of AIE photosensitive units, thereby avoiding the problem of decreased photosensitive efficiency caused by disordered aggregation and significantly improving the ability to generate reactive oxygen species.

[0026] Therefore, this photosensitizer achieves highly efficient photodynamic therapy through a network-enhanced photosensitivity mechanism. The COF framework restricts the conformation of the AIE photosensitizing unit, effectively suppressing non-radiative energy dissipation, and simultaneously generating active singlet oxygen and superoxide anions under 808nm laser irradiation, thereby realizing a mixed type I / II photosensitization process, and is suitable for NIR-II imaging-guided tumor photodynamic therapy.

[0027] In a first aspect, the present invention provides a near-infrared light-excited covalent organic framework photosensitizer, wherein the photosensitizer mBBT The general structural formula of -COF is shown in equation (I) below:

[0028] R1 is selected from S, Se or elements in the same group; R2 is selected from branched or straight-chain alkyl groups.

[0029] Specifically, the photosensitizer is a covalent organic framework structure composed of an aldehyde monomer with benzobisthiadiazole (BBT) as the core and p-phenylenediamine (PDA) through imine bond condensation. mBBT -COF.

[0030] Specifically, the present invention selects a DAD-type conjugated monomer with near-infrared II aggregation-induced emission (AIE). mBBT As a photosensitizing core, it was incorporated into a covalent organic framework to construct a highly crystalline COF photosensitizer. mBBT The monomer itself possesses a distorted molecular configuration and strong donor-acceptor interactions, but in its disordered aggregated state, it is prone to non-radiative energy dissipation, thus limiting its photosensitivity. This invention utilizes the network structure of COF... mBBT Topological constraints are imposed on the fragments, effectively limiting their conformational freedom and enabling the optically active centers to form stable and unique conformations. This promotes intersystem crossing processes and improves the generation efficiency of reactive oxygen species. This strategy cleverly utilizes the regulatory effect of a highly ordered framework on molecular arrangement, avoiding the problem of decreased photosensitivity in the aggregated state of traditional organic photosensitizers. Furthermore, COF-based photosensitizers possess both good structural stability and tunability. A polyvinylpyrrolidone (PVP)-assisted synthesis strategy can further achieve nano-scale fabrication, resulting in... mBBT n COFs possess uniform particle size, good dispersibility, and excellent colloidal stability, meeting the application requirements in biological systems. Compared with traditional small-molecule photosensitizers, the COF photosensitizing system constructed in this invention enhances photosensitivity in the aggregated state, thus being more beneficial for precise imaging and treatment of deep tumors.

[0031] In some preferred embodiments, when the photosensitizer is irradiated with an 808nm laser, the nano-photosensitizer can not only efficiently generate reactive oxygen species, but also has near-infrared II fluorescence emission characteristics, which can realize deep tissue imaging and image-guided photodynamic therapy.

[0032] Secondly, the present invention provides a method for preparing a near-infrared light-excited covalent organic framework photosensitizer, comprising the following steps: S1. Prepare the first compound containing a dialdehyde group.

[0033] In some preferred embodiments, the preparation method of the first compound includes: reacting 4,4'-((4-bromophenyl)azonyl)dibenzaldehyde and pinacol diboronic acid ester under stirring conditions with a palladium catalyst and vacuum, followed by purification by column chromatography after the reaction, as follows: .

[0034] Specifically, the preparation steps of the first compound include: reacting 4,4'-((4-bromophenyl)azonyl)dibenzaldehyde and pinacol diboronic acid ester at 100 °C for 24 h under Pd(dppf)Cl2·CH2Cl2 catalysis and vacuum conditions, and then purifying the first compound by silica gel column chromatography after the reaction is completed.

[0035] The crude product was purified by silica gel column chromatography, and ethyl acetate and n-hexane were prepared as an eluent in a volume ratio of 1:1.

[0036] S2. The first and second compounds are coupled via a palladium catalyst to prepare a DAD-type aldehyde monomer. mBBT The process is as follows: .

[0037] In some preferred embodiments, the second compound is a dibromodithiophene benzobis(selen) diazole derivative.

[0038] In some preferred embodiments, the coupling reaction is carried out under palladium catalyst catalysis and an inert gas atmosphere: the first compound and the second compound are dissolved in an organic solvent, heated to react, and then extracted, dried, and purified by column chromatography.

[0039] Specifically, the coupling reaction was carried out under the catalysis of Pd(PPh3)4 and a nitrogen atmosphere, heated at 70 °C for 4 h. After the reaction was completed, the product was extracted three times with dichloromethane, dried with Na2SO4, and purified by silica gel column chromatography (eluent: dichloromethane / n-hexane) to obtain the DAD-type monomer. mBBT It is a dark green solid.

[0040] S3. The aldehyde monomer and the amine linking unit are mixed and subjected to an imine condensation reaction under solvothermal conditions to form... mBBT COF.

[0041] In the embodiments of this application, the solvent selected for the solvothermal reaction is o-dichlorobenzene, n-butanol or acetic acid, the reaction temperature is preferably 120 °C, and the reaction time is at least 3 days.

[0042] In some preferred embodiments, the DAD-type aldehyde monomer includes a benzothiadiazole (BBT) or benzoselenide diazole acceptor, a triphenylamine (TPA) donor, and an alkyl-modified thiophene conjugated unit.

[0043] Preferably, its molecular structure includes a benzobisthiadiazole (BBT) acceptor unit, a triphenylamine (TPA) donor unit, and a thiophene conjugated bridging structure, as shown below: .

[0044] In some preferred embodiments, the amino linking unit comprises p-phenylenediamine (PDA) or 2,3,5,6-tetraamino-1,4-benzoquinone (TABQ), and when PDA is used, it can form mBBT COF; can be formed using TABQ. mBBT Q COF.

[0045] Prepared mBBT -COF has an absorption spectrum that extends to over 1100 nm, giving it the potential for near-infrared excitation. Its solid-state fluorescence peak is located at 1072 nm, making it suitable as a near-infrared II region fluorescent photosensitizer.

[0046] S4. Simultaneously with the imine condensation reaction, polyvinylpyrrolidone is added for nano-sizing to obtain a covalent organic framework photosensitizer. mBBT -nCOF.

[0047] In some preferred embodiments, the nanoforming process includes: mixing an aldehyde monomer, an amine linker and polyvinylpyrrolidone (PVP), reacting them under high-energy sonication conditions, and then resuspending and dispersing them in a buffer solution.

[0048] In this process, polyvinylpyrrolidone (PVP) is used to assist in regulating the condensation rate and suppress excessive crosslinking, thereby enabling the... mBBT COF nano-sizing, resulting in mBBT - n COF has a particle size of approximately 250 nm and can maintain stable dispersion in PBS.

[0049] In the embodiments of this application, the power of the high-energy ultrasound is preferably 200 W, and the reaction time is 2 h.

[0050] Thirdly, the present invention provides the application of a near-infrared light-excited covalent organic framework photosensitizer in the preparation of a drug for intracellular or in vivo near-infrared II imaging and photodynamic therapy.

[0051] In an optional embodiment, the photosensitizer is used for image-guided photodynamic therapy of solid tumors such as melanoma.

[0052] In some embodiments, the photosensitizer generates reactive oxygen species under 808 nm laser irradiation to induce tumor cell death.

[0053] In some embodiments, the photosensitizer has near-infrared II fluorescence emission properties and can be used for image-guided photodynamic therapy.

[0054] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0055] Example 1 This embodiment provides a method for preparing a highly crystalline photosensitizer, such as... Picture 1 As shown, it includes the following steps: S1. 3 g of 4,4'-((4-bromophenyl)azonyl)dibenzaldehyde (7.9 mmol), 3 g of pinacol diborate (11.8 mmol), 490 mg of Pd(dppf)Cl2·CH2Cl2 (0.6 mmol), and 2.32 g of potassium acetate (23.7 mmol) were dissolved in 250 mL of 1,4-dioxane solution. The mixture was stirred at 100 °C for 24 h under nitrogen protection. After the reaction was complete, water was added, and the mixture was extracted three times with ethyl acetate. The combined organic phases were dried over anhydrous magnesium sulfate, and the organic solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using a 1:1 volume ratio of ethyl acetate and n-hexane as eluent to give a pale yellow solid, compound I, in 85% yield. 577 mg of compound I (1.35 mmol), 200 mg of compound II (0.27 mmol), and 31 mg of Pd(PPh3)4 (0.027 mmol) were dissolved in 30 mL of a tetrahydrofuran / water mixture (5:1 v / v). The mixture was heated at 70 °C for 4 h under nitrogen protection. After cooling to room temperature, the mixture was extracted three times with dichloromethane (DCM) and dried over anhydrous Na2SO4. The extract was then concentrated under reduced pressure after filtration. The concentrate was purified by silica gel column chromatography (eluent: dichloromethane / n-hexane) to obtain... mBBT Product (270 mg, yield 84.6%).

[0056] S2, will mBBT It undergoes an imine condensation reaction with p-phenylenediamine (PDA) under solvothermal conditions to form mBBT COF.

[0057] S3. Polyvinylpyrrolidone (PVP) is used to assist in regulating the condensation rate and inhibit excessive crosslinking, so that the... mBBT COF nano-sizing yields mBBT n COF.

[0058] Experimental Example 1 Test probe monomer mBBT The optical properties include the following steps: The absorption spectrum was measured using an ultraviolet spectrophotometer before measurement. mBBT Completely dissolved in tetrahydrofuran, maintaining a concentration of 10 μM, the test results are as follows: Picture 2 As shown, monomer mBBT The absorption spectrum extends to 1000 nm, indicating that it has near-infrared excitation potential.

[0059] Experimental Example 2 Synthetic photosensitizers mBBT -COF and characterization of material properties include the following steps: (1) Picture 3 Based on mBBT Constructed using aldehyde monomers and PDA as amino linkage units mBBT A schematic diagram of -COF.

[0060] (2) The crystal structure of the photosensitizer powder was tested by X-ray diffraction (PXRD), and the results are as follows: Picture 4 As shown, a sharp principal diffraction peak appears at 3.25, corresponding to the hlk plane of the 110 crystal plane. The Pawley refinement of the COF structure agrees well with the experimental data, with Rwp and Rp values ​​of 7.87% and 9.14%, respectively.

[0061] (3) Its crystal structure was further tested using transmission electron microscopy (TEM), and the results are as follows: Picture 5 As shown, mBBT -COF has high crystallinity and its d-interval is 0.30 nm.

[0062] Experimental Example 3 Testing nanoscale mBBT - n The particle size and optical characteristics of COF are determined through the following steps: (1) Measurement using dynamic light scattering (DLS) method mBBT - nThe particle size of COF in phosphate buffer is as follows: Picture 7 As shown, mBBT - n COF exhibits excellent dispersibility, with a Z-average particle size of 288.3 ± 2.1 nm and a polydispersity index of 0.04.

[0063] (2) The morphology of the nanoparticles was further tested using transmission electron microscopy (TEM), and the results are as follows: Picture 6 As shown, mBBT - n COF has a uniform nanosphere morphology with a diameter of approximately 250 nm.

[0064] (3) The absorption spectrum was measured using a UV spectrophotometer, and the emission spectrum was measured using a fluorescence spectrometer. Before measurement, the sample to be tested was completely dispersed in PBS solution to maintain a concentration of 10 μg / mL. The results are as follows: Picture 8 As shown, mBBT - n COF exhibits maximum absorbance at 800 nm and displays a near-infrared II fluorescence emission peak at 1110 nm.

[0065] Test Example 4 Testing photosensitizers mBBT - n The reactive oxygen species (ROS) production capacity of COF in aqueous and cellular systems includes the following steps: (1) Mix DCFH-DA (10 μM) with the material (10 μg / mL) thoroughly, and then apply an 808 nm (0.5 W / cm) solution. 2 The DCFH was irradiated with excitation light. The fluorescence intensity changes of the emitted light at a wavelength of 525 nm were recorded at different irradiation time points.

[0066] The results are as follows Picture 9 As shown, under the same 808 nm laser irradiation conditions, compared with single-cell... mBBT Compared to its predecessor, it is 7 times more efficient at generating reactive oxygen species (ROS).

[0067] (2) Logarithmically growing B16F10 cells were digested with trypsin and then subjected to a solution of 5 × 10⁻⁶ g / mL. 3 The cells were evenly spread on a confocal dish and incubated in DMEM medium at 37 °C with 5% CO2 for 24 h to allow for full cell adhesion, thus serving as working cells. Subsequently, the cells were first... mBBT - nCells were co-cultured in COF (10 μg / mL) for 6 h, then treated with Hoechst 33342 (10 μM) for 15 min, and finally irradiated with laser. After treatment, the cells were washed with PBS and transferred to fresh medium containing 10 μM DCFH-DA for 30 min. Finally, the cells were irradiated with an 808 nm laser (0.5 W / cm²) for 10 min and observed using a confocal microscope.

[0068] The results are as follows Picture 10 As shown, compared with exposure to only 808 nm irradiation (PBS+L) or exposure to only mBBT - n Compared to other COF groups, only under 808 nm irradiation was it similar to... mBBT - n COF co-cultured cells ( mBBT - n COF+L) exhibited strong fluorescence. The results indicate that... mBBT - n COF can only effectively generate reactive oxygen species (ROS) under 808 nm irradiation (0.5 W / cm²), which is highly consistent with the basic requirements of photosensitizers: low dark toxicity, but efficient generation of reactive oxygen species after irradiation.

[0069] Experimental Example 5 Testing photosensitizers mBBT - n COF toxicity to cells includes the following steps: (1) Select logarithmically growing B16F10 cells, digest them with trypsin, and use 5×10 3 The cells were evenly spread on confocal dishes and incubated in DMEM medium at 37 °C with 5% CO2 for 24 h to allow for full cell adhesion, thus serving as working cells. Subsequently, the cells were cultured in DMEM or without... mBBT - n Cells were cultured for 6 h under COF (10 μg / mL) conditions. Afterwards, the material was thoroughly removed, and the cells were washed with PBS. The “PBS+L” group and the “…” group… mBBT - n The COF+L group was irradiated with an 808 nm laser (0.5 W / cm²) for 10 min. The cells were then washed multiple times with PBS and cultured for another 12 h. Cell viability after different treatments was assessed using standard Calcein AM / PI staining, and the cells were observed directly using a confocal microscope.

[0070] The results are as follows Picture 11 As shown, when B16F10 cells are exposed to 808 nm irradiation... mBBT - n During COF, a significant apoptosis process occurs.

[0071] (2) Select logarithmically growing B16F10 cells, digest them with trypsin, and use 5×10 3 The cells were evenly spread on confocal dishes and incubated in DMEM medium at 37 °C with 5% CO2 for 24 h to allow for full cell adhesion, thus serving as working cells. Subsequently, the cells were cultured in DMEM or without... mBBT - n Cells were cultured for 6 h under COF (10 μg / mL) conditions. Afterwards, the material was thoroughly removed, and the cells were washed with PBS. The “PBS+L” group and the “…” group… mBBT The -nCOF+L” group was irradiated with an 808 nm laser (0.5 W / cm²) for 10 min. Cells were then washed multiple times with PBS and cultured for another 6 h. After standard Annexin V-FITC / PI double staining, cells were analyzed by flow cytometry using CytExpert software (v. 2.3), followed by analysis using FlowJo software.

[0072] The results are as follows Picture 12 As shown, all control groups (PBS, PBS+L, and alone) mBBT - n No significant signs of necrosis or apoptosis were observed in the COF-treated groups, and cell viability exceeded 90% after 6 hours of incubation. However, in mBBT - n In the COF+L treatment group, cell viability significantly decreased to 72.8%, with 15.4% of cells showing signs of necrosis and 8.53% in the late apoptosis stage. Statistical analysis of PI channel signal intensity also confirmed that the number of dead cells in the photodynamic therapy group was 6 times that of the control group.

[0073] Experimental Example 6 Testing photosensitizers mBBT - n The efficacy of COF in near-infrared II fluorescence-guided photodynamic therapy (PDT) in a B16F10 melanoma model includes the following steps: Nude mice aged 6-8 weeks were used for in vivo vascular imaging experiments. After weighing, the mice were anesthetized by intraperitoneal injection of 4% avertin, and then fixed in a supine position on a self-made small animal imaging table. Injection was also performed via the tail vein. mBBT - n After COF (200 μg / mL), NIR-II window vascular imaging was performed under 808 nm light excitation through a 1065 nm long-pass filter.

[0074] The results are as follows Picture 13As shown, high-contrast vascular imaging was achieved in the major leg arteries, with a significant signal-to-background ratio (SBR) of 4.25. Biodistribution analysis results are as follows... Picture 14 As shown, mBBT - n COF, when injected via the tail vein, exhibits hepatic and splenic metabolic characteristics, and its clearance pattern is consistent with typical nanoparticle behavior.

[0075] Experimental Example 7 Testing photosensitizers mBBT - n Imaging capabilities of COF tumors and the effectiveness of PDT treatment include the following steps: Choose 6 Eight-week-old nude mice were used to establish a melanoma mouse model. After anesthetizing, the mice were given 1×10⁻⁶ mice. 6 B16F10 single-cell PBS suspension was injected into the right abdomen of each mouse, and the mouse was placed on a 37°C constant-temperature bed to maintain body temperature until it woke up from anesthesia, allowing the tumor to grow for one week. On the day of treatment, each mouse received an intratumoral injection of 50 μL of the drug solution. Thirty minutes after injection, the tumor site was imaged in near-infrared II region using an 808 nm laser, followed by 10 minutes of therapeutic irradiation. Throughout the experiment, the tumor size and body weight of all mice were monitored regularly.

[0076] The results are as follows Picture 15 As shown, the near-infrared II image clearly indicates the tumor location. Picture 16 As shown, based on mBBT - n The photodynamic therapy group, assessed by COF, showed significant tumor regression, achieving a 98.6% tumor volume growth inhibition rate compared to the phosphate-buffered saline (PBFS) control group. This remarkable tumor suppression effect is even slightly higher than that of the FDA-approved phototherapy drug ICG, which achieved a 95% tumor volume growth inhibition rate under the same conditions.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A near-infrared light-excited covalent organic framework photosensitizer, characterized in that, The general structural formula of the photosensitizer is shown in formula (I): R1 is selected from S, Se or elements in the same group; R2 is selected from branched alkyl or straight alkyl.

2. The near-infrared light-excited covalent organic framework photosensitizer according to claim 1, characterized in that, The photosensitizer generates reactive oxygen species when irradiated with a laser at a wavelength of 808 nm.

3. A method for preparing a near-infrared light-excited covalent organic framework photosensitizer as described in claim 1 or 2, characterized in that, Includes the following steps: A first compound containing a dialdehyde group was prepared; the first compound and the second compound were coupled together via a palladium catalyst to prepare a DAD-type aldehyde monomer. The aldehyde monomer and amine linker are mixed and subjected to an imine condensation reaction under solvothermal conditions. Simultaneously, polyvinylpyrrolidone is added for nano-sizing to obtain a covalent organic framework photosensitizer.

4. The method for preparing a near-infrared light-excited covalent organic framework photosensitizer according to claim 3, characterized in that, The DAD-type aldehyde monomer includes a benzothiadiazole or benzoselenide diazole acceptor, a triphenylamine donor, and an alkyl-modified thiophene conjugated unit.

5. The method for preparing a near-infrared light-excited covalent organic framework photosensitizer according to claim 3, characterized in that, The amine linker includes p-phenylenediamine or 2,3,5,6-tetraamino-1,4-benzoquinone.

6. The method for preparing a near-infrared light-excited covalent organic framework photosensitizer according to claim 3, characterized in that, The preparation method of the first compound includes: reacting 4,4'-((4-bromophenyl)azonyl)dibenzaldehyde and pinacol diboronic acid under a palladium catalyst and a vacuum condition with stirring, and then purifying by column chromatography after the reaction is completed; And / or, the second compound is a dibromodithiophene benzobis(selen) diazole derivative.

7. The method for preparing a near-infrared light-excited covalent organic framework photosensitizer according to claim 3, characterized in that, The coupling reaction was carried out under palladium catalyst catalysis and an inert gas atmosphere: the first and second compounds were dissolved in an organic solvent, heated to react, and then purified by extraction, drying, and column chromatography.

8. The method for preparing a near-infrared light-excited covalent organic framework photosensitizer according to claim 3, characterized in that, The nano-processing includes: mixing an aldehyde monomer, an amine linker and polyvinylpyrrolidone, reacting them under high-energy ultrasonic conditions, and then resuspending and dispersing them in a buffer solution.

9. The use of a near-infrared light-excited covalent organic framework photosensitizer as described in claim 1 in the preparation of a medicament for intracellular or in vivo near-infrared II imaging and photodynamic therapy.

10. The application according to claim 9, characterized in that, The drug is used to treat melanoma or other deep solid tumors.

Images