Donor-acceptor binary light-sensitive compound without heavy atom structure and preparation method and application of donor-acceptor binary light-sensitive compound

Abstract

The invention discloses a donor-acceptor binary light-sensitive compound without a heavy atom structure and a preparation method of the donor-acceptor binary light-sensitive compound. The preparation method comprises the following steps: by taking a benzothiadiazole derivative as a raw material, introducing triphenylamine through Suzuki cross-coupling reaction; nitro is reduced into amino through iron powder, then the final product, namely the binary photosensitive compound without the heavy atom structure, is generated through a Philips condensation reaction and a reaction with 9-anthracene formaldehyde, and the obtained photosensitive compound is clear in structure and has a donor-acceptor binary orthogonal special electronic structure; the compound has the properties of near-infrared fluorescence emission, high fluorescence quantum yield, high singlet oxygen generation capacity, I-type active oxygen species generation capacity and the like, has a wide application prospect in the field of tumor near-infrared light diagnosis and treatment, and opens up a new path for design of heavy-atom-free small-molecule photosensitive materials.

Description

Technical Field

[0001] This invention relates to the field of biomaterials technology, and more specifically to a donor-acceptor binary photosensitive compound without heavy atomic structure, its preparation method, and its application. Background Technology

[0002] Photodynamic immunotherapy (PDIT) is an emerging cancer treatment strategy that utilizes photosensitizers to generate reactive oxygen species (ROS) under light and oxygen exposure. This not only directly induces phototoxic reactions in tumor cells but also further stimulates the host's anti-tumor immune response, thereby achieving precise cancer treatment. Compared to traditional radiotherapy and chemotherapy, PDIT exhibits significant spatial selectivity, high repeatability, and lower toxicity. Simultaneously, PDIT induces immunogenic cell death (ICD) to release tumor-associated antigens, activating dendritic cells and T cells, further promoting a systemic anti-tumor immune response and enhancing treatment efficacy.

[0003] Photosensitizers are the core component of PDIT (Pulsed Dental Injection Therapy), and their performance directly determines the therapeutic effect. Currently, most photosensitizers rely on heavy atom effects to promote spin-orbit coupling and enhance intersystem crossing (ISC), thereby increasing ROS yield. Although these photosensitizers can generate relatively long-lived triplet states and have high ROS yields, their potential dark toxicity and poor biocompatibility limit their further clinical application. In recent years, heavy atom-free organic photosensitizers have gradually become a research hotspot due to their good biocompatibility and immunomodulatory potential (Acc. Chem. Res. 2021, 54, 1, 207-220; Chem. Soc. Rev., 2025, 54, 7025-7057; Chemical Society Review, 2025, 54, 8406-8433). These photosensitizers can improve triplet quantum yields through rational molecular design while avoiding the shortcomings of traditional heavy atom photosensitizers.

[0004] In the design of heavy atom-free photosensitizers, constructing donor-acceptor binary molecular systems is an effective strategy to improve performance. Upon photoexcitation, photoinduced electron transfer (PeT) between the donor (D) and acceptor (A) generates a charge-transfer state (¹CT), which can then form a long-lived triplet state through various pathways. The spin-orbit charge transfer intersystem crossing (SOCT-ISC) mechanism is crucial for the efficient formation of the triplet state. To achieve the SOCT-ISC mechanism, the donor and acceptor should maintain a nearly orthogonal molecular configuration and possess strong charge separation characteristics to enhance the spin-orbit coupling effect and promote electron spin flipping. Although previous studies have designed small-molecule organic photosensitizers based on acceptor-excited photoinduced electron transfer (a-PeT) and successfully generated singlet oxygen (¹O2), the design method for heavy atom-free type I photosensitizers that rely on binary orthogonal structures to achieve spatial electron transfer and efficiently drive the SOCT-ISC mechanism remains incomplete. Summary of the Invention

[0005] The purpose of this invention is to provide a novel binary photosensitive compound without heavy atomic structure and its preparation method. By constructing a donor-acceptor binary orthogonal structure system, a space electron transfer-driven SOCT-ISC process is realized, which effectively promotes the generation of triplet excited state. At the same time, this photosensitizer can generate free radical reactive oxygen species (such as O2⁻•, OH•) under hypoxic conditions, overcoming the defect of traditional type II photosensitizers being highly dependent on oxygen.

[0006] According to a first aspect of the present invention, a donor-acceptor binary photosensitive compound without heavy atoms is provided, the photosensitive compound being designated TPA-An, and having the chemical structural formula shown in Formula I: Formula I.

[0007] According to a second aspect of the present invention, a method for preparing the aforementioned donor-acceptor binary photosensitive compound without heavy atomic structure is provided, using 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole and triphenylamine 4-boronate as raw materials, and reacting according to the following reaction route: .

[0008] As an optional implementation, the preparation method includes the following steps: Under the conditions of potassium carbonate as base and tetra(triphenylphosphine)palladium as catalyst, 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole was subjected to a Suzuki coupling reaction with triphenylamine 4-boronic acid in toluene solvent, and the first intermediate was obtained after purification. The first intermediate undergoes a reduction reaction with iron powder in acetic acid solvent, and after purification, the second intermediate is obtained. The second intermediate undergoes a Phillips condensation reaction with 9-anthracene carboxaldehyde in acetic acid solvent. After purification, a donor-acceptor binary photosensitive compound without heavy atoms is obtained, denoted as TPA-An.

[0009] As an optional implementation, the molar ratio of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole, triphenylamine 4-borate, potassium carbonate, and tetra(triphenylphosphine)palladium is 1:(2~3):(0.5~1.5):0.05.

[0010] As an optional implementation, the conditions for the Suzuki coupling reaction include: reacting at 90 °C to 110 °C for 36 h to 72 h.

[0011] As an optional implementation, the molar ratio of the first intermediate to iron powder is 1:(8~12).

[0012] As an optional implementation, the conditions for the reduction reaction of the first intermediate with iron powder in acetic acid solvent include: reacting at 70 ℃ to 85 ℃ for 6 h to 8 h.

[0013] As an optional implementation, the molar ratio of the second intermediate to 9-anthracene carboxaldehyde is 1:(1.5~3).

[0014] As an optional implementation, the conditions for the Phillips condensation reaction include: reacting at 90 °C to 120 °C for 20 h to 30 h.

[0015] In a third aspect of the present invention, the use of the aforementioned donor-acceptor binary photosensitive compound without heavy atomic structure in the preparation of drugs for near-infrared fluorescence imaging, fluorescence sensors, type I photosensitizers, drugs for photodynamic immunotherapy of tumors, and optoelectronic devices is provided.

[0016] As can be seen from the above technical solution of the present invention, the donor-acceptor binary photosensitive compound without heavy atoms proposed in this invention uses imidazobenzothiadiazole as the acceptor (A) core and triphenylamine as the donor (D). A nearly orthogonal DA binary structure is constructed through Suzuki coupling and Phillips condensation reaction. This structure can effectively regulate the space charge transfer process, thereby inducing spin-orbit charge transfer system crossing (SOCT-ISC), significantly promoting the generation of triplet excited states. Simultaneously, the strong electron-donating ability of triphenylamine and the strong electron-withdrawing properties of the imidazobenzothiadiazole core synergistically form a strongly charge-separated singlet charge transfer state. 1The triplet state avoids charge backflow and can quickly transfer electrons to oxygen, resulting in efficient generation of type I ROS. In addition, the electronic structure of the imidazobenzothiadiazole core endows the photosensitive compound with a suitable redox potential, which satisfies the thermodynamic requirements for reducing oxygen to generate superoxide anions without sacrificing SOCT-ISC efficiency, ultimately achieving high triplet yield and type I ROS generation efficiency. Furthermore, the triphenylamine groups on both sides of the molecule can generate aggregation-induced emission (AIE) effect, which can significantly improve its fluorescence brightness. After self-assembling into nanoparticles, its ultraviolet absorption peak is 509 nm, the maximum emission peak of the fluorescence spectrum is 642 nm, the fluorescence quantum yield is 20.1%, and the singlet oxygen yield is 26%. Therefore, after self-assembling into nanoparticles, it can simultaneously possess the advantages of type I reactive oxygen species generation ability, high fluorescence quantum yield, high singlet oxygen yield, excellent stability, and good biocompatibility. It has great application prospects in near-infrared fluorescence imaging, fluorescence sensors, type I photosensitizers, tumor photodynamic immunotherapy, optoelectronic devices, and other applications. Attached Figure Description

[0017] Figure 1 This is a synthetic route diagram of the donor-acceptor binary photosensitive compound without heavy atomic structure according to the present invention.

[0018] Figure 2 It is the compound TPA-An in the example of this invention. 1 H-NMR spectrum.

[0019] Figure 3 It is the compound TPA-An in the example of this invention. 13 C-NMR spectrum.

[0020] Figure 4 This is the MALDI-TOF mass spectrum of compound TPA-An in the example of this invention.

[0021] Figure 5 This is a spectrum of the singlet oxygen generation capability of compound TPA-An in acetonitrile solution, as shown in the example of this invention; wherein, Figure 5 Part A in the figure shows the UV absorption spectra of DPBF in TPA-An solution at different time points. Figure 5 Part B in the figure shows the linear relationship between the absorbance of DPBF at 410 nm and the illumination time in TPA-An and RB solutions.

[0022] Figure 6 This is a dynamic light scattering test image of the TPA-An nanoparticles in the example of this invention.

[0023] Figure 7 This is the ultraviolet absorption spectrum of the TPA-An nanoparticles in the example of this invention.

[0024] Figure 8 This is the fluorescence emission spectrum of the TPA-An nanoparticles in the example of this invention.

[0025] Figure 9 This is a spectrum of the superoxide anion radical generation capability of the TPA-An nanoparticles in the example of this invention.

[0026] Figure 10 The flow cytometry diagram characterizes the mechanism of TPA-An nanoparticle-induced apoptosis in 4T1 cells under different conditions. The cells were divided into the following groups: i) 0 µg / mL TPA-An nanoparticles + dark light, ii) 0 µg / mL TPA-An nanoparticles + light, iii) 30 µg / mL TPA-An nanoparticles + dark light, iv) 30 µg / mL TPA-An nanoparticles + light.

[0027] Figure 11 This is a graph showing the adenine nucleoside triphosphate (ATP) release capacity test of TPA-An nanoparticles in this invention example.

[0028] Figure 12 This is a fluorescence imaging test image of TPA-An nanoparticles in BALB / c mice inoculated with 4T1 tumors, as described in this invention.

[0029] Figure 13 The tumor volume changes in different groups of BALB / c mice inoculated with 4T1 tumors after phototherapy. Detailed Implementation

[0030] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0031] Various aspects of the invention are described in this disclosure with reference to the accompanying drawings, in which numerous illustrative embodiments are shown. The embodiments of this disclosure are not necessarily intended to encompass all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described below in more detail, can be implemented in any of a number of ways.

[0032] The design of heavy-atom-free type I photosensitizers for SOCT-ISC driven by donor-acceptor binary orthogonal structures is incomplete, mainly due to multiple contradictions that are difficult to coordinate with the requirements of the SOCT-ISC mechanism, the need for type I ROS generation, and molecular structure regulation. First, there is a conflict between the orthogonal configuration and charge dynamics; the orthogonal configuration ensures SOCT-ISC but weakens electronic coupling, affecting electron transfer to oxygen, while strengthening coupling destroys the orthogonal configuration. Second, the triplet thermodynamics and redox potential are difficult to match; regulating the electronic properties of the donor / acceptor can easily lead to potential mismatch or a decrease in SOCT-ISC efficiency. These contradictions result in a lack of rational design strategies and universal regulation methods that simultaneously meet the requirements.

[0033] This invention constructs a donor-acceptor binary orthogonal imidazobenzothiadiazole small molecule photosensitive compound by employing a strategy of precisely controlling the molecular spatial charge distribution. Using a benzothiadiazole derivative as a raw material, triphenylamine is introduced through a Suzuki cross-coupling reaction. After reduction with iron powder, the nitro group is reduced to an amino group, and then coupled with 9-anthracene carboxaldehyde through a Phillips condensation reaction to generate the final product—a binary photosensitive compound without heavy atoms.

[0034] The obtained photosensitive compound has a well-defined structure with a unique donor-acceptor binary orthogonal electronic structure. It exhibits properties such as near-infrared fluorescence emission, high fluorescence quantum yield, high singlet oxygen generation capability, and type I reactive oxygen species generation capability. It has broad application prospects in the field of near-infrared phototherapy for tumors and opens up a new path for the design of heavy atom-free small molecule photosensitive materials. donor-acceptor binary light-sensitive compounds without heavy atomic structure

[0035] In an exemplary embodiment of the present invention, a donor-acceptor binary photosensitive compound without heavy atoms is provided. This photosensitive compound is designated as TPA-An, and its chemical structural formula is shown in Formula I: Formula I. Preparation method

[0036] Combination Figure 1 The reaction route shown in the invention provides an exemplary preparation method for a donor-acceptor binary photosensitive compound without heavy atomic structure, using 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole and triphenylamine 4-boronic acid as raw materials, comprising the following steps: Step (1): Under the conditions of potassium carbonate as base and tetra(triphenylphosphine)palladium as catalyst, 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole (compound 1) was heated and refluxed with 4-triphenylamineboric acid in toluene solution, and purified to obtain the first intermediate (compound 2). Step (2): Compound 2 was dissolved in acetic acid under a nitrogen atmosphere and reacted with iron powder under heating. After purification, the second intermediate (compound 3) was obtained. Step (3): Compound 3 was dissolved in acetic acid under a nitrogen atmosphere, and 9-anthracene carboxaldehyde was added to undergo a Phillips condensation reaction. After purification, the final product (TPA-An) was obtained.

[0037] In some embodiments, 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole is reacted with triphenylamine 4-boronic acid in toluene solvent at 90 °C to 110 °C for 36 h to 72 h, followed by extraction, drying, and column chromatography to obtain the first intermediate.

[0038] In some embodiments, the molar ratio of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole, triphenylamine 4-borate, potassium carbonate, and tetra(triphenylphosphine)palladium is 1:(2~3):(0.5~1.5):0.05.

[0039] In some embodiments, 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole is reacted with triphenylamine 4-borate in toluene solvent at 100 °C for 48 h, followed by extraction, drying, and column chromatography to obtain the first intermediate; wherein the molar ratio of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole, triphenylamine 4-borate, potassium carbonate, and tetrakis(triphenylphosphine)palladium is 1:2.5:1:0.05.

[0040] In some embodiments, the first intermediate is reacted with iron powder in acetic acid medium at 70 °C to 85 °C for 6 h to 8 h, followed by extraction, drying, and column chromatography to obtain the second intermediate.

[0041] In some embodiments, the molar ratio of the first intermediate to iron powder is 1:(8~12).

[0042] In some embodiments, the first intermediate is reacted with iron powder in acetic acid medium at 85 °C for 8 h, followed by extraction, drying, and column chromatography to obtain the second intermediate; wherein the molar ratio of the first intermediate to the iron powder is 1:10.

[0043] In some embodiments, the second intermediate is reacted with 9-anthracene carboxaldehyde in acetic acid medium at 90 °C to 120 °C for 20 h to 30 h, extracted, dried, and subjected to column chromatography to obtain the red solid final product TPA-An.

[0044] In some embodiments, the molar ratio of the second intermediate to 9-anthracene carboxaldehyde is 1:(1.5~3).

[0045] In some embodiments, the second intermediate is reacted with 9-anthracene carboxaldehyde in acetic acid medium at 100 °C for 24 h, extracted, dried, and subjected to column chromatography to obtain the red solid final product TPA-An; wherein the molar ratio of the second intermediate to 9-anthracene carboxaldehyde is 1:2. application

[0046] In another exemplary embodiment of the present invention, the application of the aforementioned donor-receptor binary photosensitive compound without heavy atomic structure is also provided in the preparation of drugs for near-infrared fluorescence imaging, fluorescence sensors, type I photosensitizers, drugs for tumor photodynamic immunotherapy, and optoelectronic devices.

[0047] In one alternative example, a photosensitizer is provided comprising the aforementioned donor-acceptor binary photosensitizer without heavy atomic structure, for example, by preparing the aforementioned imidazobenzothiadiazole small molecules into nanoparticles via nanoprecipitation, as a photosensitizer for biological applications.

[0048] To facilitate better understanding, the present invention will be further illustrated below with several specific examples, but the preparation process is not limited to these examples, and the content of the present invention is not limited to these examples.

[0049] Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market. Example 1

[0050] [according to Figure 1 Synthetic route for TPA-An]

[0051] (1) 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole (compound 1) (2.30 g, 6 mmol), triphenylamine 4-borate (4.34 g, 15 mmol), toluene (40 mL), and potassium carbonate aqueous solution (1 M, 6 mL) were added to a dry 250 mL double-necked flask. The mixture was bubbled under a nitrogen atmosphere for 5 minutes. Then, a catalyst tetra(triphenylphosphine)palladium (347 mg, 0.3 mmol) was added under a nitrogen atmosphere and the temperature was raised to 100°C. After reacting for 48 hours, the mixture was cooled to room temperature, extracted with dichloromethane, and the solvent was removed by vacuum distillation. The crude product was purified by column chromatography (dichloromethane: petroleum ether = 1:1) to obtain a purple solid intermediate (compound 2) (2.87 g, yield 67%).

[0052] The proton NMR spectrum of compound 2 is as follows: 1H NMR (400 MHz, CDCl3): δ ppm 7.41 (d, J =8.0 Hz, 4H), 7.33 (t, J = 7.6 Hz, 8H), 7.21 (t, J = 7.6 Hz, 8H), 7.14-7.09(m, 8H).

[0053] As shown above, the chemical structural formula of compound 2 is as shown in Formula II: Formula II.

[0054] (2) Compound 2 (2.14 g, 3 mmol), reduced iron powder (1.68 g, 30 mmol), and anhydrous acetic acid (25 mL) were added to a dry 100 mL double-necked flask. The reaction was heated to 85 °C and stirred vigorously for 8 hours under a nitrogen atmosphere. After the reaction was completed, the reaction was cooled to room temperature, extracted with dichloromethane, dried with anhydrous sodium sulfate, and the solvent was removed by vacuum distillation. The crude product was purified by column chromatography (dichloromethane: petroleum ether = 2:1) to obtain a yellow solid intermediate (compound 3) (1.10 g, yield 56%).

[0055] The proton NMR spectrum of compound 3 is as follows: 1 H NMR (400 MHz, CDCl3): δ ppm 7.43 (d, J =8.0 Hz, 4H), 7.28 (t, J = 7.6 Hz, 8H), 7.21 (t, J = 7.6 Hz, 12H), 7.05 (t, J= 7.6 Hz, 4H), 2.6 (s, 4H).

[0056] As shown above, the chemical structural formula of compound 3 is as shown in Formula III: Formula III.

[0057] (3) Compound 3 (653 mg, 1 mmol), 9-anthracene carboxaldehyde (412 mg, 2 mmol), and anhydrous acetic acid (20 mL) were added to a dry 100 mL double-necked flask. The reaction was heated to 100 °C under a nitrogen atmosphere and cooled to room temperature after 48 hours. The product was extracted with dichloromethane, dried with anhydrous sodium sulfate, and the solvent was removed by vacuum distillation. The crude product was purified by column chromatography (dichloromethane: petroleum ether = 1:1) to obtain the red solid final product TPA-An (688 mg, yield 82%).

[0058] like Figure 2 As shown, 1H NMR (400 MHz, DMSO-d6): δ ppm 13.26 (s, 1H), 8.88 (s,1H), 8.28-8.22 (m, 4H), 7.87 (d, J = 8.2 Hz, 2H), 7.72 (d, J = 8.6 Hz, 2H),7.61-7.51 (m, 4H), 7.33-7.28 (m, 8H), 7.09-7.04 (m, 16H). like Figure 3 As shown, 13 C NMR (101 MHz, CDCl3): δ 156.16, 151.48, 147.71, 147.30,131.25, 131.02, 130.96, 130.27, 129.29, 128.66, 127.79, 127.38, 125.63,125.16, 125.05, 123.32, 122.59. like Figure 4 As shown, MALDI-TOF MS Calculation for [M] + C 57 H 38 N6S: 838.2879, found838.0943. Combination Figures 2-4 The chemical structural formula of TPA-An can be determined as shown in Formula I: Formula I demonstrates that the present invention has successfully prepared a donor-acceptor binary photosensitive compound without heavy atomic structure. Example 2

[0059] TPA-An was dissolved in acetonitrile, and its absorbance at 520 nm was controlled to be approximately 0.3. Then, 1,3-diphenylisobenzofuran (DPBF) was added to detect the singlet oxygen generation capability of TPA-An in acetonitrile. The absorbance at 520 nm was measured using a 0.3 W / cm² laser. 2 Under irradiation, the changes in the ultraviolet spectrum of the solution were detected every 5 seconds.

[0060] like Figure 5 As shown, the absorbance of the solution at approximately 410 nm decreases with increasing illumination time, demonstrating that TPA-An effectively generates singlet oxygen under illumination. Using the photosensitizer Bengal rose red as a reference (its singlet oxygen yield in acetonitrile is 54%), the singlet oxygen yield of TPA-An in acetonitrile was measured to be 26%. Example 3

[0061] [Preparation of TPA-An Nanoparticles]

[0062] TPA-An nanoparticles were prepared by a nanoprecipitation method as follows: TPA-An (1 mg) (prepared according to the method in Example 1) and F127 (10 mg) were dissolved in tetrahydrofuran (1 mL). After sonication for 5 minutes, the solution was rapidly injected into 10 mL of deionized water and sonicated for 30 minutes. After stirring and evaporating to completely remove the tetrahydrofuran, the solution was filtered through a 0.22 μm filter to obtain a clear and transparent red TPA-An nanoparticle solution, which was stored at 4 °C for later use.

[0063] like Figure 6 As shown, the dynamic light scattering particle size distribution test results of TPA-An nanoparticles show that their hydrated particle size is 133 nm, which meets the requirements of enhanced permeability and retention (EPR). Example 4

[0064] [UV absorption and fluorescence emission tests of TPA-An nanoparticles]

[0065] A TPA-An nanoparticle solution (2.5 mL) was added to a quartz cuvette, and its ultraviolet absorption and fluorescence emission spectra were measured.

[0066] like Figure 7 and Figure 8 As shown, TPA-An nanoparticles have a maximum absorption peak of 509 nm and a maximum emission peak of 642 nm in water, with an emission tail exceeding 800 nm.

[0067] The fluorescence quantum yield was measured to be 20.1% using an integrating sphere, indicating that the TPA-An nanoparticles of this invention have good near-infrared fluorescence imaging potential. Example 5

[0068] [Test of Superoxide Anion Radical Generation Capacity of TPA-An Nanoparticles]

[0069] The superoxide anion generation performance of TPA-An was detected using the reactive oxygen species fluorescent probe dihydrorhodamine 123 (DHR123). A 520 nm laser (power density 0.3 W / cm²) was used. 2 Under irradiation, the fluorescence change of DHR123 was detected every 30 seconds.

[0070] like Figure 9 As shown, the fluorescence of DHR123 at 525 nm gradually increases with increasing illumination time, indicating that the TPA-An nanoparticles of the present invention have excellent superoxide anion generation performance.

[0071] Combined with Examples 2 and 5, it can be demonstrated that the photosensitive compound of the present invention has excellent triplet state yield and superior intersystem crossing ability. Example 6

[0072] [TPA-An Nanoparticle-Induced Apoptosis Assay in 4T1 Cells]

[0073] To investigate the mechanism of apoptosis induced by TPA-An nanoparticles after light exposure, flow cytometry was performed on 4T1 breast cancer cells. The procedure was as follows: 4T1 cells were incubated for 24 hours in six-well plates containing 2 mL of 1640 medium at 37 °C with 5% carbon dioxide. Then, the 4T1 cells were treated with different methods: i) 0 µg / mL TPA-An nanoparticles without light, ii) 0 µg / mL TPA-An nanoparticles with light, iii) 30 µg / mL TPA-An nanoparticles without light, and iv) 30 µg / mL TPA-An nanoparticles with light. Flow cytometry analysis was performed. The light dose in the light-exposed group was 0.05 W / cm². 2 The light exposure time is 5 minutes.

[0074] like Figure 10 As shown, TPA-An nanoparticles exhibit low dark toxicity and high phototoxicity, primarily leading to cell death through late apoptosis. Example 7

[0075] [Adenosine Triphosphate (ATP) Release Assay of TPA-An Nanoparticles]

[0076] To investigate the mechanism of immunogenic cell death induced by TPA-An nanoparticles after photoexcitation, ATP release was tested in 4T1 breast cancer cells. The method was as follows: 4T1 cells were incubated for 24 hours in a six-well plate containing 2 mL of 1640 medium at 37 ℃ with 5% carbon dioxide. Then, the 4T1 cells were treated with different methods: i) 0 µg / mL TPA-An nanoparticles + dark light, ii) 0 µg / mL TPA-An nanoparticles + 520 nm laser light, iii) 30 µg / mL TPA-An nanoparticles + dark light, and iv) 30 µg / mL TPA-An nanoparticles + 520 nm laser light. A commercially available luciferase-luciferase ATP luminescence assay kit was used according to the manufacturer's instructions.

[0077] like Figure 11As shown, under light conditions, the ATP release level of cells in group iv) increased significantly, providing a signal for the recruitment and maturation of dendritic cells, and further enhancing the anti-tumor immune effect. This demonstrates that the TPA-An nanoparticles of the present invention have the ability to induce immunogenic cell death under light conditions, thereby effectively activating dendritic cells and enhancing the effect of tumor immunotherapy. Example 8

[0078] [In vivo fluorescence imaging assay of TPA-An nanoparticles in mice]

[0079] A 4T1 tumor-bearing mouse model was established by subcutaneous injection of 4T1 cancer cells. TPA-An nanoparticles (200 μL, 200 μg / mL) were injected into mice via the tail vein, and fluorescence images of the tumor site were recorded at different time points (1, 2, 4, 8, 12, 24, 36 hours).

[0080] like Figure 12 As shown, after intravenous injection of TPA-An nanoparticles into mice, the fluorescence signal at the tumor site gradually increased over time, reaching a maximum at 8 hours, and then gradually weakened. Example 9

[0081] [Tumor Therapeutic Performance Testing of TPA-An Nanoparticles]

[0082] Sixteen BALB / c mice subcutaneously inoculated with 4T1 tumor cells were selected as tumor models and randomly divided into four groups. Tumor volumes ranged from 100 to 150 mm. 3 Different treatments were administered via tail vein injection every two days: Group 1 received saline solution plus a dark light control group; Group 2 received saline solution plus a light control group; Group 3 received TPA-An nanoparticles plus a dark light control group; and Group 4 received TPA-An nanoparticles plus a light therapy group. In Groups 3 and 4, the injection dose was 100 μL at a concentration of 0.1 mg / mL, while Groups 1 and 2 received an equal volume of saline solution. After injection, all four groups underwent dark light treatment. Eight hours later, Groups 2 and 4 received 520 nm laser light irradiation at a dose of 0.1 W / cm². 2 The irradiation time is 8 minutes; the first and third groups do not receive any light.

[0083] like Figure 13 As shown, the tumors in the fourth group of mouse tumor models basically disappeared after three treatments, demonstrating the excellent photodynamic therapy effect of heavy atom photosensitizer-free treatment, which can completely eliminate tumors.

[0084] As demonstrated by the above tests, the imidazobenzothiadiazole-type heavy atom-free small molecule photosensitive compound of the present invention can enhance the ability to generate reactive oxygen species through the spin-orbit charge transfer intersystem crossing (SOCT-ISC) mechanism induced by its donor-acceptor binary structure. Furthermore, it can still induce tumor cell apoptosis through type I photodynamic therapy under hypoxic conditions, providing a new approach for the development of heavy atom-free small molecule photosensitive materials.

[0085] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A donor-acceptor binary photosensitive compound without heavy atomic structure, characterized in that, The photosensitive compound is designated as TPA-An, and its chemical structural formula is shown in Formula I:

2. A method for preparing a donor-acceptor binary photosensitive compound without heavy atomic structure as described in claim 1, characterized in that, The following reaction route was followed to prepare the product using 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole and triphenylamine 4-boronic acid as starting materials:

3. The method for preparing the donor-acceptor binary photosensitive compound without heavy atomic structure according to claim 2, characterized in that, The preparation method includes the following steps: Under the conditions of potassium carbonate as base and tetra(triphenylphosphine)palladium as catalyst, 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole was subjected to a Suzuki coupling reaction with triphenylamine 4-boronic acid in toluene solvent, and the first intermediate was obtained after purification. The first intermediate undergoes a reduction reaction with iron powder in acetic acid solvent, and the second intermediate is obtained after purification. The second intermediate undergoes a Phillips condensation reaction with 9-anthracene carboxaldehyde in acetic acid solvent. After purification, a donor-acceptor binary photosensitive compound without heavy atoms is obtained, denoted as TPA-An.

4. The method for preparing the donor-acceptor binary photosensitive compound without heavy atomic structure according to claim 3, characterized in that, The molar ratio of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole, triphenylamine 4-borate, potassium carbonate, and tetra(triphenylphosphine)palladium is 1:(2~3):(0.5~1.5):0.

05.

5. The method for preparing the donor-acceptor binary photosensitive compound without heavy atomic structure according to claim 3, characterized in that, The conditions for the Suzuki coupling reaction include reacting at 90 °C to 110 °C for 36 h to 72 h.

6. The method for preparing the donor-acceptor binary photosensitive compound without heavy atomic structure according to claim 3, characterized in that, The molar ratio of the first intermediate to iron powder is 1:(8~12).

7. The method for preparing the donor-acceptor binary photosensitive compound without heavy atomic structure according to claim 3, characterized in that, The conditions for the reduction reaction of the first intermediate with iron powder in acetic acid solvent include: reacting at 70 ℃~85 ℃ for 6 h~8 h.

8. The method for preparing the donor-acceptor binary photosensitive compound without heavy atomic structure according to claim 3, characterized in that, The molar ratio of the second intermediate to 9-anthracene carboxaldehyde is 1:(1.5~3).

9. The method for preparing the donor-acceptor binary photosensitive compound without heavy atomic structure according to claim 3, characterized in that, The conditions for the Phillips condensation reaction include reacting at 90 °C to 120 °C for 20 h to 30 h.

10. The use of the donor-acceptor binary photosensitive compound without heavy atomic structure as described in claim 1 in the preparation of drugs for near-infrared fluorescence imaging, fluorescence sensors, type I photosensitizers, drugs for photodynamic immunotherapy of tumors, and optoelectronic devices.

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