Photosensitizing dyes with non-conjugated n-methyl site and preparation method and application thereof

Abstract

This invention discloses a class of non-conjugated N-methyl site-linked photosensitive dyes, their preparation methods, and applications, relating to the field of fine chemical organic dye technology. The photosensitive dyes have the structure of general formula 1. These non-conjugated N-methyl site-linked photosensitive dyes possess no heavy atom modification, dual-cation characteristics, and exhibit near-infrared absorption and emission, high molar extinction coefficient, and high photosensitization efficiency, specifically generating type I and type II reactive oxygen species. They demonstrate excellent tumor cell killing ability under near-infrared light irradiation, showing promising application prospects in anti-tumor therapy.

Description

Technical Field

[0001] This invention relates to the field of fine chemical organic dyes technology, and in particular to non-conjugated N-methyl site-linked photosensitive dyes, their preparation methods, and applications. Background Technology

[0002] Photodynamic therapy (PDT) is a non-invasive, safe, and highly effective tumor treatment method that utilizes photoexcitation to generate an excited state in a photosensitive dye. This excited state then undergoes intersystem crossing to reach a triplet state, transferring energy or electrons to surrounding oxygen molecules to produce reactive oxygen species, which in turn kill cells. As the foundation and core of PDT technology, high-performance photosensitive dyes for phototherapy must possess advantages such as good stability, controllable excited-state properties, and high efficiency in non-radiative energy release during excited-state transitions (high reactive oxygen species yield and high photothermal conversion efficiency).

[0003] Cyanide dyes, as conventional and typical photosensitive dyes, possess advantages such as tunable excitation wavelength, high molar extinction coefficient, good biocompatibility, and easy structural modification. However, their poor stability and low photosensitization efficiency severely limit their commercial application. Studies have shown that dicationic cyanide dyes exhibit better stability and water solubility, higher photosensitization efficiency, and tumor-specific targeting capabilities. Currently, conventional preparation strategies mainly rely on linking the non-conjugated mesylate chain of the cyanide dye to the mesophyll via an aromatic linker arm. However, the cumbersome synthetic steps, stringent molecular structure requirements, and limited modifiable groups pose significant obstacles to further development. Summary of the Invention

[0004] To address the shortcomings of cyanine dyes in photosensitization performance, this invention provides a non-conjugated N-methyl site-linked photosensitive dye, its preparation method, and its application. By modifying the non-conjugated N-methyl site of cyanine dyes, a one-step reaction can simultaneously achieve molecular quaternization and the preparation of cyanine dye core molecules with dual-cationic characteristics. Moreover, the diverse modifiable groups are more conducive to the regulation of structure and performance.

[0005] To achieve the above objectives, the technical solution of the present invention is: a non-conjugated N-methyl site-linked photosensitive dye having the structure shown in general formula 1 below.

[0006]

[0007] In general formula 1, R1 and R2 can be the same or different, and R1 and R2 are each independently selected from any one of methyl, ethyl, long-chain alkoxy, benzyl, alkyl sulfonic acid group, and tumor-targeting group;

[0008] X is selected from one of iodine, chlorine, and bromine;

[0009] Y1, Y2, Y3, and Y4 may be the same or different, and each of Y1, Y2, Y3, and Y4 is independently selected from one of the following: dimethyl, oxygen, sulfur, and selenium.

[0010] n is any positive integer; preferably, n is 1, 3 or 5;

[0011] A is selected from any one of the groups described in formulas A-1 to A-9:

[0012]

[0013] In general formulas A-1 to A-3, R3, R3', R4, R5, and R5' may be the same or different, and each of R3, R3', R4, R5, and R5' is independently selected from any one of hydrogen, fluorine, chlorine, bromine, methyl, ethyl, long-chain alkyl, and long-chain alkoxy.

[0014] In general formula 1, B1, B2, B3, and B4 can be the same or different, and each of B1, B2, B3, and B4 can be independently selected from any one of the structures shown in the following structural formulas B-1 to B-3;

[0015]

[0016] In the B-1 group, R6 is selected from any one of hydrogen, fluorine, chlorine, bromine, carboxylic acid group, and sulfonic acid group.

[0017] Furthermore, the tumor-targeting group is selected from any one of rituximab, bevacizumab, estrogen receptor, epidermal growth factor receptor, folic acid, and biotin.

[0018] Furthermore, in general formula 1, B1 and B4 are the same, B2 and B3 are the same, and B1 and B2 are different. The same B1 and B4 are selected from the structures shown in the following structural formulas B-1 or B-2.

[0019]

[0020] In the B-1 group, R6 is selected from any one of hydrogen, fluorine, chlorine, bromine, carboxylic acid group, and sulfonic acid group.

[0021] Furthermore, the photosensitive dye linked to the non-conjugated N-methyl site is selected from one of the compounds shown in Formulas 1-1 to 1-15 below:

[0022]

[0023] Furthermore, the photosensitive dye linked to the non-conjugated N-methyl site has absorption and emission wavelengths of 750–900 nm in the near-infrared region; the molar extinction coefficient of the photosensitive dye linked to the non-conjugated N-methyl site in the near-infrared I region is 2.8–3.5 × 10⁻⁶.5 M -1 cm -1 .

[0024] A method for preparing a non-conjugated N-methyl site-linked photosensitive dye includes the following steps: the compound shown in general formula 2 and the compound shown in general formula 3 undergo a Knoevenagel condensation reaction in an organic acid anhydride, an organic base, and a nonpolar solvent at a molar ratio of 2 to 5:1 to generate a near-infrared biscationic cyanine dye shown in formula 1.

[0025]

[0026] In general formula 2, B is selected from B1, B2, B3 or B4.

[0027] Furthermore, the synthesis process of the compound described in Formula 3 is as follows:

[0028]

[0029] Furthermore, the organic acid anhydride is selected from any one of acetic anhydride, propionic anhydride, succinic anhydride, benzoic anhydride, and phthalic anhydride, and the molar ratio of the compound represented by general formula 3 to the organic acid anhydride is 1:1.5 to 2.5.

[0030] Furthermore, the organic base is selected from triethylamine, pyridine, and N,N-diisopropylethylamine, and the molar ratio of the compound represented by general formula 3 to the organic base is 1:4 to 5.

[0031] Furthermore, the nonpolar solvent is selected from one of dichloromethane, trichloromethane, and dichloroethane.

[0032] Non-conjugated N-methyl site-linked photosensitive dyes are used in the fields of bioimaging and medical diagnosis and treatment, preferably for photodynamic therapy of tumors.

[0033] Furthermore, for normoxic and hypoxic photodynamic antitumor therapy, the aforementioned dual-cationic cyanine dye exhibits highly efficient mitochondrial targeting ability and (type I and type II) reactive oxygen species generation under near-infrared light radiation, and can be used for antitumor photodynamic therapy.

[0034] In summary, the present invention has the following beneficial effects:

[0035] 1. Based on non-conjugated N-methyl site linkage, this application designs and synthesizes a bicationic cyanine dye with strong absorption and emission spectra in the near-infrared region (main absorption spectrum located at 650 nm–750 nm, main emission spectrum located at 750 nm–850 nm), however, its molar extinction coefficient is increased several times (2.8–3.5 × 10⁻⁶). 5 M -1 cm -1It has a stronger light absorption capacity;

[0036] 2. Due to its dual-cationic structure, the non-conjugated N-methyl site-linked photosensitive dye prepared in this application has a stronger specific targeting function for mitochondria; it can be excited by near-infrared light to generate type I and type II reactive oxygen species, which can be used to efficiently kill tumor cells.

[0037] 3. Testing revealed that the dyes described in this application exhibit significant improvements in properties such as molar extinction coefficient and reactive oxygen species yield compared to traditional cyanine dyes. Under light conditions, they demonstrate excellent cell-killing ability. Conversely, under dark conditions, these cyanine dyes exhibit good biocompatibility. In the embodiments of this application, different concentrations of the photosensitive dyes showed that MCF-7 cells retained over 90% cell viability after 48 hours of culture, indicating that they do not produce toxic side effects on cells within the working concentration range. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a high-resolution mass spectrometry of the photosensitive dye 2o-Cy disclosed in this invention;

[0040] Figure 2 This is the high-resolution mass spectrometry of the photosensitive dye 2m-Cy disclosed in this invention;

[0041] Figure 3 This invention provides a high-resolution mass spectrometry representation of the photosensitive dye 2p-Cy.

[0042] Figure 4 The absorption and emission spectra of the three photosensitive dyes (2o-Cy, 2m-Cy, 2p-Cy) disclosed in this invention in dichloromethane are shown.

[0043] Figure 5 This invention discloses the types and capabilities of reactive oxygen species (ROS) generated by the three photosensitive dyes (2o-Cy, 2m-Cy, 2p-Cy) in different reactive oxygen probes.

[0044] Figure 6 These are confocal fluorescence imaging images of the three photosensitive dyes (2o-Cy, 2m-Cy, and 2p-Cy) disclosed in this invention targeting mitochondria in MCF-7 cells.

[0045] Figure 7The image shows the MTT assay results of the three photosensitive dyes (2o-Cy, 2m-Cy, and 2p-Cy) disclosed in this invention in MCF-7 cells. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the appendices in the embodiments of the present invention. Figure 1-7 The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] The following detailed description, in conjunction with specific embodiments, illustrates a class of biscationic cyanine dyes based on non-conjugated N-methyl sites, as shown in Formula 1.

[0048] Bicationic cyanine dyes based on non-conjugated N-methyl sites have the following general structural formula 1

[0049]

[0050] In general formula 1, R1 and R2 can be independently selected from any one of methyl, ethyl, long-chain alkoxy, benzyl, alkyl sulfonic acid, and tumor-targeting groups;

[0051] X is selected from one of iodine, chlorine, and bromine;

[0052] Y1, Y2, Y3, and Y4 can be independently selected from one of the following: dimethyl, oxygen, sulfur, and selenium atoms;

[0053] n is any positive integer; preferably, n is 1, 3 or 5;

[0054] A can be any one of the groups described in formulas A-1 to A-9:

[0055]

[0056] In formulas A-1 to A-3, R3, R3', R4, R5, and R5' can be independently selected from any one of hydrogen, fluorine, chlorine, bromine, methyl, ethyl, long-chain alkyl, and long-chain alkoxy.

[0057] B1, B2, B3, and B4 can be independently selected from the structures shown in B-1 to B-3 below;

[0058]

[0059] In the B-1 group, R6 is selected from any one of hydrogen, fluorine, chlorine, bromine, carboxylic acid group, and sulfonic acid group.

[0060] The following are specific examples of compounds represented by general formula 1, but the present invention is not limited to these specific examples.

[0061]

[0062] The present invention can be synthesized from the compound represented by general formula 1 by the method described in the following examples.

[0063] The synthesis processes involved in Examples 1-3 are shown below:

[0064]

[0065] Example 1

[0066] Bicationic cyanine dyes based on non-conjugated N-methyl sites, where R1 is selected from ethyl, X from bromine, Y from dimethyl, and n from 1;

[0067] A is selected from B is selected from

[0068] Its synthesis method includes the following steps:

[0069] (1) Synthesis of compound BBYD-Et

[0070] 1,1,2-Trimethyl-1H-benzo[e]indole (designated BBYD) (4 g, 19.11 mmol) and 1-iodoethane (3.28 g, 21.02 mmol) were dissolved in acetonitrile (35 mL). After stirring and refluxing at 110 °C for 12 hours, a large amount of ethyl acetate was added and the mixture was filtered. The residue was a blue solid product (3.82 g, yield 83.92%, designated BBYD-Et), which could be used for the next step without further purification.

[0071] (2) Synthesis of compound M1

[0072] The mixture of BBYD-Et (3 g, 12.6 mmol) synthesized in step (1) and (1E,3E)-N,N-diphenylpropane-1,3-diimine (3 g, 13.5 mmol) was dissolved in acetic acid (13 mL) and acetic anhydride (13 mL). The solvent was stirred and heated at 125 °C under a nitrogen atmosphere for 1 hour. The mixture was poured into 20 mL of methanol. The solvent was removed by rotary evaporation, and the crude product was recrystallized from methyl tert-butyl ether. The product was a deep red solid (4.5 g, yield 86.75%, named M1), and its structure was identified by nuclear magnetic resonance spectroscopy.

[0073] 1H NMR (400MHz, DMSO) δ8.92(d,J=13.2Hz,1H),8.64(dd,J=15.1Hz,1H),8.37(d,J=8.5Hz,1H),8 .22(d,J=8.9Hz,1H),8.17(d,J=8.2Hz,1H),7.98(d,J=8.9Hz,1H),7.76(t,J=7.3Hz,1H),7.68 (d,1H),7.65(d,2H),7.60(d,J=5.1Hz,1H),7.47(d,J=7.3Hz,2H),6.94(d,J=15.2Hz,1H),5. 57(dd,J=11.3Hz,1H),4.47(q,J=7.0Hz,2H),2.04(s,3H),1.93(s,6H),1.33(t,J=7.1Hz,3H). 13 C NMR (101MHz, DMSO) δ181.34,172.47,156.61,138.56,137.67,133.19,131.34,130.91,130.45,130.09,129.10 ,128.95,128.73,127.42,127.12,123.38,119.42,113.39,113.14,111.20,53.39,27.31,26.13,21.54,13.83.

[0074] (3) Synthesis of general formula 3(2o)

[0075] Compound BBYD (1.4 mmol) was mixed with A-2Br (1,2-di(bromomethyl)benzene, named o-2Br) in toluene under nitrogen protection and reacted at 100 °C for 12 h. The reaction was stopped, and after the mixture returned to room temperature, it was added to excess diethyl ether. A grayish-white solid powder, named 2o, was prepared by recrystallization. This compound did not require purification and was used directly in the next reaction.

[0076] (4) Synthesis of compound 2o-Cy

[0077] To address the issue of low yield caused by traditional synthesis methods for the final target photosensitive dye in this embodiment, the ratio of organic acids and organic bases involved in the reaction and the selection of solvents were optimized, as shown in parallel experiments 1-6 in Table 1.

[0078] Table 1. Experimental Optimization Statistics

[0079] Serial Number organic acids Organic bases solvent Yield % Parallel Experiment 1 Acetic anhydride (0.1 mL) Triethylamine (0.1 mL) dichloromethane ～3.6 Parallel Experiment 2 Acetic anhydride (0.1 mL) Triethylamine (0.3 mL) dichloromethane ～22.3 Parallel Experiment 3 Acetic anhydride (0.1 mL) Triethylamine (0.5 mL) dichloromethane ～65.6 Parallel Experiment 4 Acetic anhydride (0.1 mL) Triethylamine (0.8 mL) dichloromethane ～18.2 Parallel Experiment 5 Acetic anhydride (0.1 mL) Triethylamine (0.5 mL) chloroform ～10.8 Parallel Experiment 6 Acetic anhydride (0.1 mL) Triethylamine (0.5 mL) dichloroethane ～9.6

[0080] As can be seen from Table 1, by statistically analyzing the average yield of multiple parallel experiments in the same batch, it was found that the product yield was highest when the reaction conditions shown in Parallel Experiment 3 were followed. Therefore, the synthesis of photosensitive dye molecules in subsequent examples was carried out in accordance with Parallel Experiment 3.

[0081] Triethylamine (0.5 mL) and acetic anhydride (0.1 mL) were added to a dichloromethane solution containing M1 (1.5 mmol) and 2o (1 mmol), respectively. The reaction was carried out at 90 °C for 3 h under nitrogen protection. The solution was then poured into 250 mL of tert-butyl methyl ether and filtered to obtain a blue-black solid. The crude product was purified by silica gel column chromatography using dichloromethane / methanol (v / v, 20 / 1) as the eluent. The product, a blue-black solid, was named 2o-Cy, with a yield of 65.6%. Its theoretical high-resolution mass spectrometry value is M[C78H76N4]. 2+ =534.3032, the actual measured value is 534.3056(2o-Cy), see [reference]. Figure 1 .

[0082] Example 2

[0083] The only difference from Example 1 is that 1,3-di(bromomethyl)benzene, named m-2Br, is used instead of A-2Br (1,2-di(bromomethyl)benzene, named o-2Br; A is...).

[0084] The product obtained using the method in Example 2 of this application is named 2m-Cy, with a yield of 53.3%, and its theoretical high-resolution mass spectrometry value is M[C]. 78 H 76 N4] 2+ = 534.3032, actual measured value 534.3044 (2m-Cy), see [reference]. Figure 2 .

[0085] Example 3

[0086] The only difference from Example 1 is that 1,4-di(bromomethyl)benzene, named p-2Br, is used instead of A-2Br (1,2-di(bromomethyl)benzene, named o-2Br; A is...).

[0087] The product obtained using the method in Example 2 of this application is named 2p-Cy, with a yield of 64.2%, and its theoretical high-resolution mass spectrometry value is M[C]. 78 H 76 N4] 2+ = 534.3032, actual measured value 534.3031 (2p-Cy), see [reference]. Figure 3 .

[0088] Comparative Example

[0089] The comparative example, Cy5.5, is a commercially available dye with the structure shown below. Its maximum absorption and emission peaks are located at 691 nm and 720 nm, respectively. This product is available from commercial pharmaceutical companies and has a purity of >99.5%.

[0090]

[0091] Performance testing

[0092] The 2o-Cy, 2m-Cy, and 2p-Cy obtained in the above examples were dried, accurately weighed, and dissolved in dimethyl sulfoxide to prepare a 2.0 mM DMSO dye stock solution. These solutions were then placed in 1.50 mL brown sample vials and stored in a refrigerator for future use.

[0093] 1. Photophysical performance testing

[0094] Test method: 20 μL of dye stock solution was dissolved in 3.00 mL of dichloromethane. The absorption spectrum of the dye was measured at room temperature using a UV-Vis spectrophotometer, and the fluorescence spectrum was measured using a fluorescence method. The commercially available dye Cy5.5 was used as the reference photosensitive dye. The test results are shown in [link to test results]. Figure 4 .

[0095] from Figure 4 It can be seen that the maximum absorption of 2o-Cy, 2m-Cy, and 2p-Cy is located in the near-infrared region, at 692, 693, and 693 nm, respectively. Compared with the maximum absorption of Cy5.5 (690 nm), the absorption is redshifted by 2-3 nm, while the fluorescence emission remains essentially unchanged. It is noteworthy that the shoulder peak at 650 nm is more prominent for 2o-Cy, 2m-Cy, and 2p-Cy than for Cy5.5. The calculated molar extinction coefficients of 2o-Cy, 2m-Cy, and 2p-Cy are 34.7, 28.8, and 31.9 × 10⁻⁶, respectively. 4 M -1 cm -1 The molar extinction coefficients of 2o-Cy, 2m-Cy, and 2p-Cy are 2.8-3.5 times that of Cy5.5. At the same concentration, 2o-Cy, 2m-Cy, and 2p-Cy have larger molar extinction coefficients than Cy5.5, which means they have stronger absorption capabilities for photons. Therefore, the dual-cationic cyanine dyes designed and synthesized in this patent exhibit strong absorption and emission spectra in the near-infrared region, and the molar extinction coefficients have been increased several times, resulting in stronger light absorption capabilities, making them more suitable for tissue imaging and tumor treatment in near-infrared scenarios.

[0096] 2. Reactive oxygen species test

[0097] Dihydrorhodamine 123 (DHR123), singlet oxygen green fluorescent probe (SOSG), hydroxyphenyl fluorescein (HPF), and superoxide anion fluorescent probe (DHE) were used as reactive oxygen species (ROS), singlet oxygen species (SOSG), hydroxyl radicals (HPF), and superoxide anion scavengers, respectively. All of them reacted with the responding ROS to produce bright fluorescence. The excitation and emission of the different probes were as follows: DHR123:λ ex =500nm; λ em =536nm; SOSG:λ ex =504nm; λ em =525nm; HPF:λ ex =492nm; λ em =515nm; DHE:λ ex =535nm; λ em =610nm; the laser radiation for the photosensitizer is 660nm, 5mW cm⁻¹. -2 The concentrations of 2o-Cy, 2m-Cy, and 2p-Cy were all 1 μM, and Cy5.5 was 2 μM. The test results showed... Figure 5 .

[0098] from Figure 5 It can be seen that the fluorescence intensity of DHR123 in 2p-Cy gradually increases with the extension of laser irradiation time, indicating that 2p-Cy can generate reactive oxygen species more easily than other photosensitive dyes. Simultaneously, the fluorescence intensity of SOSG continuously increases with the participation of 2o-Cy, 2m-Cy, and 2p-Cy, indicating that all can generate singlet oxygen, and the enhancement is several times greater than that of Cy5.5. However, in HPF, 2o-Cy and 2m-Cy are similar to Cy5.5, producing almost no hydroxyl radicals; only the HPF solution of 2p-Cy shows strong fluorescence, indicating that 2p-Cy can generate type I reactive oxygen species. Finally, the fluorescence of DHE containing photosensitive dyes shows a certain degree of recovery, indicating that all can generate superoxide anions, with 2o-Cy showing a stronger generating ability. Therefore, the non-conjugated N-methyl-linked dicationic cyanine dyes prepared in this application can be excited by near-infrared light to generate type I and type II reactive oxygen species, which can be used to efficiently kill tumor cells.

[0099] 3. Cell colocalization experiment

[0100] MCF-7 cells were cultured in DMEM with 10% FCS. 1 μM of the photosensitive dyes 2o-Cy, 2m-Cy, and 2p-Cy were added to the culture medium containing MCF-7 cells and incubated at 37°C. Uptake was then determined using confocal imaging. The excitation wavelength of the photosensitive dyes was 650 nm, and the emission wavelength of the probes was 730 nm.

[0101] The photosensitive dye was readily taken up by MCF-7 cells. The concentration of the photosensitive dye was 1 μM, and the concentration of MTG (mitochondrial) was 100 nM. First, 1 μM of the photosensitive dye was added to three dishes containing MCF-7 cells and incubated for 2 hours. Then, 100 nM of each of the three commercially available dyes was added to the cell culture dishes and incubated separately, followed by laser confocal imaging. The excitation wavelength of the photosensitive dye was 660 nm, and the receiving wavelength was 730 nm. The excitation wavelength of the MTG was 488 nm, and the receiving wavelength was 515-545 nm. The test results are shown in... Figure 6 middle.

[0102] from Figure 6 It can be seen that the photosensitive dye can be well localized in the mitochondria of MCF-7 cells.

[0103] 4. Phototoxicity experiment of photosensitive dyes on MCF-7 cells

[0104] Test method: The MCF-7 cells to be tested were digested with 0.25% trypsin and resuspended in DMEM culture medium containing 10% fetal bovine serum. The cells were then cultured at a density of 10 cells per well. 3 ~10 4 100 μL of cells were seeded into 96-well plates. The plates were then transferred to a cell culture incubator and incubated at 37°C, 5% CO2, and saturated humidity for 24 hours. Different concentrations of photosensitive dye were then added, and the cells were cultured for another 2 hours. Subsequently, a 660 nm, 20 mW / cm² photosensitive dye was used. 2 Irradiate each well with a near-infrared light source. After irradiation, place the 96-well plate in an incubator for 24 hours. Add 20 μL of MTT solution (5 mg / mL) to each well and incubate for 4 hours. Terminate the culture and carefully aspirate the culture supernatant from the wells. Then, add 100 μL of DMSO to each well and shake for 10 minutes to fully dissolve the crystals. Measure the absorbance at 490 nm in each well using a microplate reader and calculate the cell viability: (Experimental group absorbance / Control group absorbance) × 100%. See [link to results]. Figure 7 .

[0105] from Figure 7 As can be seen, the non-conjugated N-methyl-linked bis-cationic cyanine dyes prepared in this application all exhibit excellent tumor cell killing ability under light conditions. Conversely, under dark conditions, the photosensitizing dyes at different concentrations still showed more than 90% cell viability after culturing MCF-7 cells for 48 hours, indicating that these cyanine dyes do not produce toxic side effects on cells within the working concentration range and have good biocompatibility.

[0106] Based on the above, this application takes the non-conjugated N-methyl site as a breakthrough point, uses aromatic compounds as linker groups and indole groups as donor groups, and utilizes the steric hindrance effect and push-pull electron effect of the linker groups and donor groups to design and synthesize a series of novel biscation photosensitive dyes, which simultaneously possess multiple functions such as good stability, strong tumor-specific targeting, high photosensitization efficiency, generation of type I reactive oxygen species, and excellent anti-tumor phototherapy effect.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A photosensitive dye with a non-conjugated N-methyl site linkage, characterized in that, The photosensitive dye linked to the non-conjugated N-methyl site is selected from one of the compounds shown in the following formula: 。 2. The photosensitive dye with non-conjugated N-methyl sites linked according to claim 1, characterized in that, The photosensitive dye linked to the non-conjugated N-methyl site has absorption and emission wavelengths of 750–900 nm in the near-infrared region; the molar extinction coefficient of the photosensitive dye linked to the non-conjugated N-methyl site in the near-infrared I region is 2.8–3.5 × 10⁻⁶. 5 M -1 cm -1 .

3. The method for preparing the non-conjugated N-methyl site-linked photosensitive dye according to claim 1, characterized in that, Includes the following steps: The compounds shown in general formula 2 and general formula 3 are subjected to Knoevenagel condensation reaction in an organic acid anhydride, an organic base and a nonpolar solvent at a molar ratio of 2 to 5:1 to generate the near-infrared biscation cyanine dye shown in general formula 1. In the general formula, Y is selected from Y1 or Y4; A, X, n, R1, Y1, Y2, Y3, Y4, B, B2 and B3 are selected from the compounds defined in claim 1.

4. The preparation method according to claim 3, characterized in that, The organic acid anhydride is selected from any one of acetic anhydride, propionic anhydride, succinic anhydride, benzoic anhydride, and phthalic anhydride, and the molar ratio of the compound represented by general formula 3 to the organic acid anhydride is 1:1.5~2.

5.

5. The preparation method according to claim 3, characterized in that, The organic base is selected from triethylamine, pyridine, and N,N-diisopropylethylamine, and the molar ratio of the compound represented by general formula 3 to the organic base is 1:4~5.

6. The preparation method according to claim 3, characterized in that, The nonpolar solvent is selected from one of dichloromethane, trichloromethane, and dichloroethane.

7. The use of the non-conjugated N-methyl site-linked photosensitive dye according to claim 1 or 2 in bioimaging and tumor photodynamic therapy formulations.

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