Preparation method and application of photosensitizer for type I photodynamic therapy synergistic photothermal therapy

Abstract

The application belongs to the technical field of antitumor drugs, and specifically discloses a preparation method and application of a photosensitizer for type I photodynamic therapy and synergistic photothermal therapy. The chemical structure of the photosensitizer is shown in formula (I). Due to the heavy atom effect of the sulfur atom, the photosensitizer can improve the coupling constant, is beneficial to intersystem crossing of the exciton, improves the active oxygen yield of the photosensitizer XM, and has good photodynamic therapy effect. The rotor type triphenylamine unit can ensure active intramolecular motion even in an aggregated state, so that heat can be effectively generated under photon excitation, and the photothermal therapy effect is good. The photosensitizer can generate O2 ‑ with cytotoxicity, kill tumor cells, and convert absorbed photon energy into heat energy to cause local high temperature, so as to achieve the treatment purpose of inhibiting tumor growth. The preparation method of the photosensitizer has the advantages of easy availability of raw materials, mild synthesis conditions, simple preparation method, convenient purification, easy realization, and great application prospect.

Description

Technical Field

[0001] This invention belongs to the field of antitumor drug technology, specifically relating to a preparation method and application of a photosensitizer for type I photodynamic therapy combined with photothermal therapy. Background Technology

[0002] Current cancer treatment primarily relies on traditional surgical resection, supplemented by chemotherapy and radiotherapy. While traditional methods offer some effectiveness, they also have limitations, such as a high recurrence rate and significant drug side effects. Photodynamic therapy (PDT) complements traditional methods to some extent. For example, PDT offers advantages such as good tissue selectivity, non-invasiveness, rapid onset of action, resistance to drug resistance, fewer systemic side effects, and the ability to be repeated, and it can also work synergistically with other treatment methods. Photothermal therapy (PTT) offers advantages such as high specificity, precise controllability, and minimal damage to normal tissues. However, neither PDT nor PTT alone is sufficient to ablate tumors, as each faces limitations that hinder their overall success. For instance, elevated temperatures may not be enough to eliminate tumors, and the hypoxic microenvironment of tumor tissue may limit the production of reactive oxygen species. Therefore, compared to standalone treatment systems, PDT combined with PTT can provide greater biocompatibility, accuracy, and efficiency in cancer diagnosis and treatment.

[0003] Photodynamic therapy utilizes excited-state photosensitizers to generate energy through singlet-triplet phototransformation, allowing ground-state oxygen to gain energy or through photo-oxidation to form singlet oxygen (Type II mechanism), or through reaction with other biomolecules to form numerous reactive oxygen species (ROS, Type I mechanism), which are then used to kill cancer cells. Photothermal therapy converts absorbed photon energy into heat energy, causing localized high temperatures that ultimately kill tumor cells.

[0004] Most reported photosensitizers are type II photosensitizers that primarily generate singlet oxygen. However, the ROS generation process of type II photosensitizers is highly dependent on oxygen, and their ROS generation efficiency is often limited by the hypoxic conditions of tumor tissue. In contrast, type I photosensitizers have been shown to have better hypoxia tolerance and can fully utilize the limited oxygen in the tumor microenvironment during photodynamic therapy. Furthermore, some studies have confirmed that photothermal therapy can not only increase vascular saturated oxygen concentration by increasing blood flow velocity but also enhance the absorption of photodynamic therapy drugs by tumor cells, thus improving overall treatment efficacy. Therefore, combining type I photodynamic therapy with photothermal therapy is considered a more feasible strategy to overcome tumor hypoxia and heterogeneity and achieve better anti-tumor treatment effects. Moreover, based on its important role in maintaining cell growth, resisting cell death, and activating cancer cell invasion and metastasis, the cell nucleus is considered the optimal target for photodynamic therapy. Therefore, developing photosensitizers that combine type I photodynamic therapy with photothermal therapy can overcome the hypoxia problem faced by traditional oxygen-dependent type II photosensitizers in tumor photodynamic therapy, and the combined photothermal therapy has better effects than photodynamic therapy or photothermal therapy alone, which is of great significance for the treatment of tumors. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a photosensitizer for type I photodynamic therapy combined with photothermal therapy.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned photosensitizer for type I photodynamic therapy combined with photothermal therapy.

[0007] Another object of the present invention is to provide the application of the above-mentioned photosensitizer in the preparation of photosensitizers for tumor phototherapy (photodynamic therapy combined with photothermal therapy), especially in the preparation of photosensitizers for type I tumor photodynamic therapy combined with photothermal therapy.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A photosensitizer for use in type I photodynamic therapy combined with photothermal therapy, named XM, has the chemical structure shown in formula (I):

[0010]

[0011] In the formula, R1 is hydrogen or a straight-chain or branched alkyl group with 1-30 carbon atoms, and R1 is in the para position. The presence or absence of alkyl side chains in the XM structure leads to different solubilities, but the difference is not significant. The XM structure with alkyl side chains exhibits superior photodynamic / photothermal synergistic therapeutic effects compared to the XM structure without alkyl side chains. The preferred number of carbon atoms in the alkyl side chains in the XM structure is 1-8. Within this range, the alkyl chain length is moderate, the target product is determined to be a solid, and it is easier to weigh and use accurately.

[0012] Preferably, R1 is hydrogen or a straight-chain or branched alkyl group having 1-8 carbon atoms, for example: R1 is hydrogen, methyl, a straight-chain or branched alkyl group having 4 carbon atoms, a straight-chain or branched alkyl group having 8 carbon atoms, etc., and R1 is in the para position.

[0013] More preferably, R1 is hydrogen or a straight-chain or branched alkyl group having 1-4 carbon atoms, for example: R1 is hydrogen, methyl, a straight-chain or branched alkyl group having 4 carbon atoms, etc., and R1 is in the para position.

[0014] The most preferred form is R1, which is hydrogen, tert-butyl, methyl, n-octyl, n-butyl, or 2-ethylhexyl, with R1 in the para position; the structural formula corresponding to formula (Ⅰ)XM is as follows:

[0015]

[0016] The preparation method of the above-mentioned photosensitizer for type I photodynamic therapy combined with photothermal therapy includes the following steps:

[0017] 2,7-Dibromobenzo[2,1-b:3,4-b']dithiophene-4,5-dione and 4-(R1-yl)-N-(4-(R1-yl)phenyl)-N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoborane-2-yl)phenyl)aniline undergo a Suzuki coupling reaction with toluene as solvent under an inert atmosphere (such as argon) catalyzed by tetrakis(triphenylphosphine)palladium and potassium carbonate. The reaction temperature is 80–110 °C, and the reaction time is 12–30 minutes. The reaction was carried out for 15 hours (preferably 12 hours at 80°C). The product was purified by silica gel column chromatography using a mixed solvent of petroleum ether and dichloromethane (volume ratio of petroleum ether to dichloromethane 4:1) to obtain compound 2,7-bis(4-(bis(4-(R1-yl)phenyl)amino)phenyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione (XM); wherein the R1 group is a hydrogen or a straight-chain or branched alkyl group with 1-30 carbon atoms, and R1 is in the para position.

[0018] Further, the molar ratio of 2,7-dibromobenzo[2,1-b:3,4-b']dithiophene-4,5-dione to 4-(R1-yl)-N-(4-(R1-yl)phenyl)-N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoborane-2-yl)phenyl)aniline, tetra(triphenylphosphine)palladium, and potassium carbonate is 1:2-3:0.02-0.2:5-10, preferably 1:3:0.05:8, and the molar amount of 2,7-dibromobenzo[2,1-b:3,4-b']dithiophene-4,5-dione to the volume ratio of toluene is 1 mmol:(15-30) mL, preferably 1 mmol:20 mL.

[0019] The specific preparation route of the photosensitizer used in type I photodynamic therapy combined with photothermal therapy is as follows:

[0020]

[0021] The above-mentioned photosensitizers and the photosensitizers synthesized by the above methods are used in the preparation of photosensitizers for tumor phototherapy (photodynamic therapy combined with photothermal therapy), especially in the preparation of photosensitizers for type I tumor photodynamic therapy combined with photothermal therapy.

[0022] In a specific application, the photosensitizer and the amphiphilic polymer are dissolved in an organic solvent, then ultrapure water is added to the system, and the system is sonicated to make it uniformly dispersed. Then the organic solvent is removed to obtain water-soluble photosensitizer nanoparticles, the apparent concentration of which is ≥360μg / mL.

[0023] Furthermore, the organic solvent is selected from one of tetrahydrofuran, 1,4-dioxane, N,N-dimethylformamide, and ethyl acetate.

[0024] Furthermore, the amphiphilic polymer is F127 (an amphoteric triblock polymer formed by ethoxy-propoxy), DSPE-mPEG2000 (distearylphosphatidylethanolamine-polyethylene glycol 2000), or DSPE-mPEG5000 (distearylphosphatidylethanolamine-polyethylene glycol 5000).

[0025] Furthermore, the tumors mentioned are cervical cancer, skin cancer, osteosarcoma, etc.

[0026] This invention relates to a photosensitizer for type I photodynamic therapy combined with photothermal therapy. Due to the heavy atom effect of sulfur atoms, it can increase the coupling constant, facilitating intersystem crossing of excitons and increasing the yield of reactive oxygen species generated by the photosensitizer XM, resulting in better photodynamic therapy effects. The rotor-type triphenylamine (TPA) derivative ensures active intramolecular motion even in the aggregated state, effectively generating heat through non-radiative transitions to achieve photothermal therapy effects. Under xenon lamp irradiation (wavelength range 300-750nm), it rapidly generates cytotoxic superoxide anion radicals (O2) via a photochemical pathway of electron transfer. - Furthermore, it can convert absorbed photon energy into heat energy, causing localized high temperatures, ultimately killing tumor cells, thus achieving the goal of type I photodynamic therapy combined with photothermal therapy to inhibit tumor growth. The photosensitizer of this invention uses readily available raw materials, has mild synthesis conditions, is simple to prepare, and is easy to purify, making it highly promising for application.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] 1. The photosensitizer XM of this invention, due to the heavy atom effect of sulfur atoms, can expand the spin-orbit coupling constant between singlet and triplet states, which is beneficial for intersystem crossing of excitons and increases the yield of reactive oxygen species generated by photosensitizer XM, resulting in good photodynamic therapy effects. The rotor-type triphenylamine unit can ensure active intramolecular motion even in the aggregated state, thereby effectively generating heat under photon excitation, resulting in good photothermal therapy effects.

[0029] 2. The photosensitizer XM of the present invention is a photosensitizer that can be used for photodynamic therapy and photothermal therapy of tumors. It is non-toxic to cancer cells under normal culture conditions and has good biocompatibility. Under xenon lamp irradiation (wavelength range of 300-750nm), it has the characteristic of high damage effect on cancer cells. The cancer cells are preferably cervical cancer cells, such as HeLa cells.

[0030] 3. Photosensitizers rapidly generate superoxide anion radicals (O2) through electron transfer. - It can also convert absorbed light energy into heat energy, and photodynamic therapy combined with photothermal therapy kills tumor cells to achieve the therapeutic goal of inhibiting tumor growth. It is mainly based on type I photodynamic therapy and has good hypoxia resistance characteristics.

[0031] 4. The preparation method of the photosensitizer XM of the present invention uses readily available raw materials, has mild synthesis conditions, is simple to prepare, and is convenient to purify. Attached Figure Description

[0032] Figure 1 UV-Vis absorption spectra of photosensitizer XM2 in different solvents.

[0033] Figure 2Fluorescence emission spectrum of photosensitizer XM2 under illumination of DHR123.

[0034] Figure 3 Figure: Temperature change of photosensitizer XM2 under 660nm laser irradiation.

[0035] Figure 4 Photothermal curves of photosensitizer XM2 under 660nm laser irradiation on / off cycles.

[0036] Figure 5 Figure: Results of photodynamic therapy combined with photothermal therapy on HeLa cells by photosensitizer XM2 nanoparticles. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0038] Example 1: Preparation of compound XM1

[0039] (1) Preparation of photosensitizer (XM1)

[0040] Under an argon atmosphere, 2,7-dibromobenzo[2,1-b:3,4-b']dithiophene-4,5-dione (purchased from Shenzhen Ruixun Optoelectronic Materials Technology Co., Ltd., 3.8 g, 10.11 mmol), N,N-diphenyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxoborane-2-yl)aniline (11.26 g, 30.33 mmol), tetrakis(triphenylphosphine)palladium (0.59 g, 0.51 mmol), potassium carbonate (11.16 g, 80.88 mmol), and 202.20 mL of toluene were added to a 500 mL two-necked flask. The mixture was heated to 80 °C and reacted for 12 hours. After the reaction was stopped, the reaction was quenched with water, then extracted with dichloromethane and dried with anhydrous magnesium sulfate. The solution was concentrated and then purified by silica gel column chromatography using a mixed solvent of petroleum ether and dichloromethane (volume ratio of petroleum ether to dichloromethane 4:1) as the eluent. After drying, solid compound XM1 was obtained with a yield of 72%. MS and elemental analysis results showed that the obtained compound was the target product. The chemical reaction equations for the preparation process are shown below:

[0041]

[0042] XM1 (chemical structural formula is C) 46 H 30 The theoretical molecular weight of N2O2S2 is 706.20, and the result measured by matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF) is 707.40 [M+H]. +The contents of C, H, N, O, and S in XM1 were determined using a PerkinEXMer elemental analyzer (model EA-2400II). The theoretical values ​​were: C: 78.16%; H: 4.28%; N: 3.96%; O: 4.53%; S: 9.07%. The measured values ​​were: C: 78.30%; H: 4.22%; N: 3.93%; O: 4.48%; S: 9.07%. The mass spectrometry and elemental analysis results were close to the theoretical values, proving that the synthesized product was indeed the target product.

[0043] (2) Preparation of nanoparticles

[0044] To adapt to the complex aquatic environment in organisms, 4 mg of oil-soluble photosensitizer XM1 and 60 mg of amphiphilic polymer F127 (an amphoteric triblock polymer formed by ethoxy-propoxy) were completely dissolved in 0.4 mL of tetrahydrofuran solution. Under sonication, the mixture was quickly added to 4 mL of ultrapure water and sonicated for another 10 min to ensure uniform dispersion. Nitrogen gas was then bubbled into the sample to remove the tetrahydrofuran. Finally, the sample was stored at 4 °C for later use.

[0045] The apparent concentration of the prepared water-soluble XM1 nanoparticles (XM1 NPs) was 1000 μg / mL. The size of the XM1 NPs was measured using a Malvern laser particle size analyzer (Mastersizer 3000), and the results showed that the particle size was 82 nm and the polydispersity index (PDI) was 0.16.

[0046] Example 2: Preparation of compound XM2

[0047] (1) Preparation of photosensitizer (XM2)

[0048] Under an argon atmosphere, 2,7-dibromobenzo[2,1-b:3,4-b']dithiophene-4,5-dione (3.8 g, 10.11 mmol), 4-(tert-butyl)-N-(4-(tert-butyl)phenyl)-N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoborane-2-yl)phenyl)aniline (14.66 g, 30.33 mmol), tetrakis(triphenylphosphine)palladium (0.59 g, 0.51 mmol), potassium carbonate (11.16 g, 80.88 mmol), and 202.20 mL of toluene were added to a 500 mL two-necked flask. The mixture was heated to 80 °C and reacted for 12 hours. After the reaction was stopped, the reaction was quenched with water, then extracted with dichloromethane and dried with anhydrous magnesium sulfate. The solution was concentrated and then purified by silica gel column chromatography using a mixed solvent of petroleum ether and dichloromethane (volume ratio of petroleum ether to dichloromethane 4:1) as the eluent. After drying, solid compound XM2 was obtained with a yield of 70%. MS and elemental analysis results showed that the obtained compound was the target product. The chemical reaction equations for the preparation process are shown below:

[0049]

[0050] XM2 (chemical structural formula is C) 62 H 62 The theoretical molecular weight of N2O2S2 is 930.40, while the result obtained by matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF) is 931.80 [M+H]. + The contents of C, H, N, O, and S in XM2 were determined using a PerkinEXMer elemental analyzer (model EA-2400II). The theoretical values ​​were: C: 79.96%; H: 6.71%; N: 3.01%; O: 3.44%; S: 6.88%. The measured values ​​were: C: 80.07%; H: 6.62%; N: 3.00%; O: 3.51%; S: 6.80%. The mass spectrometry and elemental analysis results were close to the theoretical values, proving that the synthesized product was indeed the target product.

[0051] (2) Preparation of nanoparticles

[0052] To adapt to the complex aquatic environment in organisms, 4 mg of oil-soluble photosensitizer XM2 and 40 mg of amphiphilic polymer F127 (an amphoteric triblock polymer formed by ethoxy-propoxy) were completely dissolved in 0.4 mL of tetrahydrofuran solution. Under sonication, the mixture was quickly added to 4 mL of ultrapure water and sonicated for another 10 min to ensure uniform dispersion. Nitrogen gas was then bubbled into the sample to remove the tetrahydrofuran. Finally, the sample was stored at 4 °C for later use.

[0053] The apparent concentration of the prepared water-soluble XM2 nanoparticles (XM2 NPs) was 1000 μg / mL. The size of the XM2 NPs was measured using a Malvern laser particle size analyzer (Mastersizer 3000), and the results showed that the particle size was 70 nm and the polydispersity index (PDI) was 0.17.

[0054] The presence or absence of alkyl side chains in a compound's structure leads to different solubilities. Specifically, the presence of alkyl substituents and the longer the alkyl chain, the better the solubility, resulting in fewer amphiphilic polymers needed for nanoparticle preparation and smaller particle sizes. Therefore, comparing photosensitizers XM1 and XM2 with the same conjugated backbone and identical photophysical properties, XM2-based nanoparticles have smaller particle sizes, making them more suitable for biological applications. Thus, XM2 is more suitable as a photosensitizer.

[0055] Figure 1The images show the UV-Vis absorption spectra of XM2 in dichloromethane (DCM), ethyl acetate (EA), tetrahydrofuran (THF), and toluene (TOL) solutions, measured using a PerkinElmer Lambda 950 UV-Vis spectrophotometer. The test wavelength range is 300–1000 nm. The graphs show that the absorption spectrum of XM2 is in the range of 300–900 nm, exhibiting strong absorption in the near-infrared region, indicating that XM2 possesses photothermal conversion properties.

[0056] Dihydrorhodamine 123 (DHR123) is itself a cell membrane-permeable fluorescent probe (λ). Ex / λ Em The fluorescence intensity (495 / 620 nm) can be used to detect superoxide anion radicals (O2-). Based on the fluorescence enhancement, the amount and changes of cellular ROS content can be determined. To verify that XM2 is a type I photosensitizer for photodynamic therapy, 4 μL of DHR123 (10 mmol / L) was added to 2.0 mL of XM2 NPs solution with a concentration of 2 μmol / L. The sample was then tested using a fluorescence spectrometer with an excitation wavelength of 495 nm and a wavelength range of 500–620 nm. See the specific fluorescence spectrum below. Figure 2 After the addition of DHR123, fluorescence increased in the 500–620 nm range over time (2–10 min). This indicates that XM2 is a type I photosensitizer suitable for photodynamic therapy.

[0057] Under irradiation with a 660 nm laser, the concentration of XM2 nanosolution (50 μmol / L XM2 NPs) was measured at 400 mW / cm². 2 600mW / cm 2 800mW / cm 2 1000mW / cm 2 The temperature rise under power, such as Figure 3 As shown. At a power of 400mW / cm 2 At that time, the XM2 nanosolution temperature increased from 21.5℃ to 30.7℃; the power was 600mW / cm. 2 At that time, the XM2 nanosolution temperature increased from 20.6℃ to 34.2℃; the power was 800mW / cm. 2 At that time, the XM2 nanosolution temperature increased from 23.4℃ to 32.3℃; the power was 1000mW / cm. 2 At this temperature, the XM2 nanoparticle solution increased from 23.1℃ to 52.3℃. The results indicate that the optimal concentration of the XM2 nanoparticle solution (50 μmol / L) and the illumination power (1000 mW / cm²) are suitable for this process. 2 At that time, XM2 had good photothermal performance.

[0058] Figure 4 The photothermal curves of XM2 nanosolution (XM2 NPs concentration of 50 mg / mL) under 660 nm laser irradiation on / off cycles are shown. Specifically, the XM2 nanosolution was irradiated with a 660 nm laser at 1000 mW / cm². 2 Irradiation was carried out for 8 minutes, followed by an 8-minute break. Temperature was measured every 30 seconds, and this cycle was repeated four times. As shown in the figure, the structure of XM2 did not change before and after irradiation.

[0059] The cytotoxicity of XM2 cells and the synergistic effect of photodynamic and photothermal therapy on HeLa cells were detected using the CCK-8 assay. The specific experimental steps are as follows:

[0060] 1) Dilute the 500 μg / mL nanoparticle stock solution to concentrations of 20 μg / mL, 40 μg / mL, 60 μg / mL, 80 μg / mL, and 100 μg / mL using complete culture medium (DMEM, containing 10% fetal bovine serum, 100 U / mL penicillin, and 100 μg / mL streptomycin).

[0061] 2) HeLa cells (human cervical cancer cells, ATCC) in the logarithmic growth phase were digested with 0.25% trypsin and the cells were uniformly diluted to a concentration of 5 × 10⁻⁶. 4 Cells / mL.

[0062] 3) Add the cell solution to each well of a 96-well plate (100 μL), shake gently to mix, and then incubate at 37°C and 5% CO2 for 24 h.

[0063] 4) Add 100 μL of complete culture medium containing different concentrations of XM2 nanoparticles to 96-well plates, with 20 wells for each concentration. Form four groups of five wells each: one control group (no light) and three experimental groups (light). The experimental groups include a single-photodynamic group (xenon lamp: 80 W / cm²). 2 Illumination duration 5 min), single photothermal group (660nm laser: power 1000mW / cm²) 2 The study included two groups: a 5-minute light irradiation group and a synergistic treatment group (simultaneous 5-minute xenon lamp and 660nm laser irradiation at the same power). A 0 μg / mL control group was included. The 96-well plates were incubated for 12 hours.

[0064] 5) Remove the 96-well plate from the experimental group (light-illuminated group) and heat it with a xenon lamp (power 80W / cm²). 2 ) and / or a 660nm laser (power 1000mW / cm) 2 After irradiation for 5.0 min, the plates were placed in an incubator and cultured for another 12 h. The control group (non-illuminated group) of 96-well plates did not require light treatment and were directly cultured for 24 h.

[0065] 6) Wash away the waste culture medium from the 96-well plates of the experimental group (light group) and the control group (no light group), add 100 μL of complete culture medium containing 10% CCK-8 to each well, and then put them back into the incubator for 1 hour.

[0066] 7) Place the 96-well plates of the experimental group (light-exposed group) and the control group (no-light-exposed group) into a microplate reader and measure the absorbance of each well at the absorption peak at 450 nm. Calculate the average and standard deviation of the absorbance of the five wells in each group, and then calculate the cancer cell survival rate. The CCK-8 assay results are shown below. Figure 5 .

[0067] from Figure 5 It was found that under light-free conditions, the survival rate of HeLa cells remained above 93% at different concentrations of XM2 NPs, indicating that XM2 NPs exhibited excellent biocompatibility under light-free conditions. However, under light conditions, cell survival rate was related to the concentration of XM2 NPs; the higher the concentration, the lower the cell survival rate. For the single photodynamic therapy group, at a concentration of 20 μg / mL, XM2 NPs killed 20.2% of HeLa cells; at 40 μg / mL, it killed 29.8%; at 60 μg / mL, it killed 45.5%; at 80 μg / mL, it killed 59.9%; and at 100 μg / mL, it killed 61.3%. For the single photothermal group, XM2 NPs killed 14.6% of HeLa cells at a concentration of 20 μg / mL; 26.6% at 40 μg / mL; 35.8% at 60 μg / mL; 48.8% at 80 μg / mL; and 54.4% at 100 μg / mL. In the synergistic treatment group, XM2 NPs killed 27.5% of HeLa cells at a concentration of 20 μg / mL; 31.7% at 40 μg / mL; 50.2% at 60 μg / mL; 62.8% at 80 μg / mL; and 71.4% at 100 μg / mL. These data demonstrate that XM2 NPs exhibit excellent photodynamic / photothermal synergistic therapeutic effects on HeLa cells under phototherapy.

[0068] The same method was used to evaluate the photodynamic therapy combined with photothermal therapy of XM1 NPs, except that the complete culture medium containing different concentrations of XM2 NPs in step (4) was replaced with a complete culture medium containing different concentrations of XM1 NPs. Under light-free conditions, the survival rate of HeLa cells with different concentrations of XM1 NPs remained above 92%, indicating that XM1 NPs exhibit excellent biocompatibility under light-free conditions. Under light-free conditions, however, cell survival rate was related to the concentration of XM1 NPs; the higher the concentration of XM1 NPs, the lower the cell survival rate. For the single photodynamic therapy group, XM1 NPs killed 18.4% of HeLa cells at a concentration of 20 μg / mL; 27.3% at 40 μg / mL; 43.6% at 60 μg / mL; 57.5% at 80 μg / mL; and 59.8% at 100 μg / mL. For the single photothermal group, XM1 NPs killed 12.1% of HeLa cells at a concentration of 20 μg / mL; 24.4% at 40 μg / mL; 33.6% at 60 μg / mL; 46.5% at 80 μg / mL; and 52.6% at 100 μg / mL. In the synergistic treatment group, XM1 NPs killed 25.7% of HeLa cells at a concentration of 20 μg / mL; 29.9% at 40 μg / mL; 48.3% at 60 μg / mL; 60.4% at 80 μg / mL; and 69.8% at 100 μg / mL. The experimental data are summarized in Table 1 below. This data demonstrates that under light irradiation, XM2 NPs exhibit a superior photodynamic / photothermal synergistic therapeutic effect on HeLa cells compared to XM1 NPs.

[0069] Table 1. Cell lethality of XM1 NPs and XM2 NPs at different concentrations and under different conditions.

[0070]

[0071] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A photosensitizer for use in type I photodynamic therapy combined with photothermal therapy, the chemical structure of which is shown in formula (Ⅰ): （Ⅰ） In the formula, R1 is a hydrogen or a straight-chain or branched alkyl group with 1-30 carbon atoms, and R1 is in the para position.

2. The photosensitizer for type I photodynamic therapy combined with photothermal therapy according to claim 1, characterized in that: In formula (Ⅰ), R1 is a straight-chain or branched alkyl group with 1-8 carbon atoms, and R1 is in the para position.

3. The photosensitizer for type I photodynamic therapy combined with photothermal therapy according to claim 2, characterized in that: In formula (Ⅰ), R1 is a straight-chain or branched alkyl group with 1-4 carbon atoms, and R1 is in the para position.

4. The photosensitizer for type I photodynamic therapy combined with photothermal therapy according to claim 2, characterized in that: In formula (Ⅰ), R1 is methyl, n-butyl, tert-butyl, n-octyl, or 2-ethylhexyl, with R1 in the para position.

5. The method for preparing the photosensitizer for type I photodynamic therapy combined with photothermal therapy according to any one of claims 1-4, characterized in that, The preparation route of formula (Ⅰ)XM is as follows: ； Wherein, the R1 group is defined in the same way as the group in the corresponding claims 1-4.

6. The method for preparing the photosensitizer for type I photodynamic therapy combined with photothermal therapy according to claim 5, characterized in that, Includes the following steps: 2,7-Dibromobenzo[2,1-b:3,4-b']dithiophene-4,5-dione and 4-(R1-yl)-N-(4-(R1-yl)phenyl)-N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoborane-2-yl)phenyl)aniline were subjected to a Suzuki coupling reaction with toluene as solvent under an inert atmosphere and catalyzed by tetra(triphenylphosphine)palladium and potassium carbonate. The reaction was carried out at 80-110°C for 12-15 hours. The product was purified by silica gel column chromatography using a mixture of petroleum ether and dichloromethane as eluent to obtain the compound 2,7-bis(4-(bis(4-(R1-yl)phenyl)amino)phenyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione.

7. The method for preparing the photosensitizer for type I photodynamic therapy combined with photothermal therapy according to claim 6, characterized in that: The molar ratio of 2,7-dibromobenzo[2,1-b:3,4-b']dithiophene-4,5-dione to 4-(R1-yl)-N-(4-(R1-yl)phenyl)-N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoborane-2-yl)phenyl)aniline, tetra(triphenylphosphine)palladium, and potassium carbonate is 1:2~3:0.02~0.2:5~10, and the molar amount of 2,7-dibromobenzo[2,1-b:3,4-b']dithiophene-4,5-dione to the volume ratio of toluene is 1 mmol:(15~30) mL.

8. The method for preparing the photosensitizer for type I photodynamic therapy combined with photothermal therapy according to claim 7, characterized in that: The molar ratio of 2,7-dibromobenzo[2,1-b:3,4-b']dithiophene-4,5-dione to 4-(R1-yl)-N-(4-(R1-yl)phenyl)-N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoborane-2-yl)phenyl)aniline, tetra(triphenylphosphine)palladium, and potassium carbonate was 1:3:0.05:8, and the molar amount of 2,7-dibromobenzo[2,1-b:3,4-b']dithiophene-4,5-dione to the volume ratio of toluene was 1 mmol:20 mL.

9. The method for preparing the photosensitizer for type I photodynamic therapy combined with photothermal therapy according to claim 6, characterized in that: The eluent is a mixture of petroleum ether and dichloromethane in a volume ratio of 4:

1.

10. The use of the photosensitizer according to any one of claims 1-4 or the photosensitizer prepared by any one of claims 5-9 in the preparation of photosensitizers for tumor phototherapy.

11. The use of the photosensitizer according to any one of claims 1-4 or the photosensitizer prepared by any one of claims 5-9 in the preparation of photosensitizers for combined photodynamic therapy and photothermal therapy of type I tumors.

12. The use of the photosensitizer according to any one of claims 1-4 or the photosensitizer prepared by any one of claims 5-9 in the preparation of photosensitizers for photodynamic therapy combined with photothermal therapy for cervical cancer, skin cancer, and osteosarcoma type I.

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