A long-absorbing wavelength polymethine cyanine molecule, preparation method and application thereof

Abstract

The application provides a long-absorption-wavelength polymethine cyanine molecule, a preparation method and application, and compound II, compound III and acetate are added into acetic anhydride, stirred at a certain temperature, and treated with an organic solvent to obtain compound I. The application has the beneficial effects that the compound in the application has an absorption wavelength of more than 1200nm and a photo-thermal conversion efficiency of 83.2%.

Description

Technical Field

[0001] This invention belongs to the field of compound synthesis technology, and in particular relates to a long absorption wavelength polymethyl cyanine molecule, its preparation method, and its application. Background Technology

[0002] Near-infrared II (NIR-II, 1000-1700 nm) absorption organic small-molecule photothermal agents possess advantages such as good biocompatibility, low phototoxicity, and deeper tissue penetration, making them popular among researchers in the field of photothermal therapy. Currently, various NIR-II photothermal materials are being continuously developed to construct therapeutic systems, including quantum dots, rare earth elements, and organic small molecules. Because organic small molecules have well-defined structures, are easily metabolized, and possess great structural versatility, their photothermal properties can be well-designed through fine-tuning of their molecular structure. However, due to challenges in synthesis and the lack of suitable molecular frameworks, developing organic small-molecule photothermal agents that simultaneously possess high photothermal conversion efficiency and NIR-II absorption remains a challenging task.

[0003] Currently, near-infrared II photothermal agents face challenges in terms of performance, such as short absorption wavelengths and generally low photothermal conversion efficiency. Summary of the Invention

[0004] In view of this, the present invention aims to propose a long absorption wavelength polymethyl cyanine molecule, its preparation method and application, in order to solve the problems of short absorption wavelength and generally low photothermal conversion efficiency faced by external second-zone photothermal agents.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A polymethyl cyanine molecule with a long absorption wavelength, compound I comprising the following structure

[0007]

[0008] One of them;

[0009] R1 is

[0010] R2 is H or R2 and R3 form a ring, wherein the ring is one of benzene ring and naphthalene;

[0011] R3 is H or R3 and R2 form a ring, wherein the ring is one of benzene ring and naphthalene; or R3 and R4 form a ring, wherein the ring is one of benzene ring and naphthalene.

[0012] R4 and R5 are H or methyl, or R4, R5 and R3 form a ring, wherein the ring is one of benzene ring, naphthalene, and anthracene.

[0013] A method for preparing polymethyl cyanine molecules with long absorption wavelengths includes the following steps:

[0014] Compound II, Compound III, and acetate were added to acetic anhydride, stirred at a certain temperature, and treated with an organic solvent to obtain Compound I;

[0015] Compound II is

[0016] Compound III is One of them;

[0017] R1 is

[0018] R2 is H or R2 and R3 form a ring, wherein the ring is one of benzene ring and naphthalene;

[0019] R3 is H or R3 and R2 form a ring, wherein the ring is one of benzene ring and naphthalene; or R3 and R4 form a ring, wherein the ring is one of benzene ring and naphthalene.

[0020] R4 and R5 are H or methyl, or R4 and R5 form a ring with R3, wherein the ring is one of benzene ring, naphthalene, and anthracene;

[0021] Preferably, the acetate includes one of sodium acetate and potassium acetate;

[0022] Preferably, the temperature is 30-50℃;

[0023] Preferably, the stirring time is 4-6 hours.

[0024] Furthermore, the compound includes:

[0025]

[0026]

[0027] One of them.

[0028] Furthermore, in compound I, R2 and R3 are H, and R4 and R5 are methyl or R2 and R3 are cyclic, wherein the ring is one of benzene ring and naphthalene, and R4 and R5 are methyl;

[0029] The preparation method of compound I includes the following steps:

[0030] G1: Under a protective atmosphere, compound IV and 1-iodohexadecane were dissolved in an organic solvent and heated to obtain compound II;

[0031] G2: Compound II, Compound III, and acetate were added to acetic anhydride, stirred at a certain temperature, and treated with an organic solvent to obtain Compound I;

[0032] Compound IV includes:

[0033] Compound II is

[0034] Compound III is One of them;

[0035] R1 is

[0036] Furthermore, the protective gas in step G1 includes one of argon and nitrogen, more preferably, the protective gas is argon;

[0037] Preferably, the organic solvent in step G1 includes chloroform;

[0038] Preferably, the heating temperature in step G1 is 60-100℃;

[0039] Furthermore, the acetate in step G2 includes one of sodium acetate or potassium acetate;

[0040] Preferably, the temperature in step G2 is 30-50℃;

[0041] Preferably, the stirring time in step G2 is 4-6 hours.

[0042] Furthermore, in compound I, R2 is H, and R3, R4, and R5 are cyclic, wherein the ring is one of benzene, naphthalene, or anthracene;

[0043] The preparation method of compound I includes the following steps:

[0044] H1: Compound V, sodium hydride, N,N-dimethylformamide, and 1-iodohexadecane are mixed and reacted in an ice bath. After heating, reactant VI is obtained.

[0045] H2: Under the action of a protective gas, compound VI, methyl magnesium chloride and solvent are mixed, stirred at a certain temperature, cooled, neutralized by adding acid solution, and then iodide is added to obtain compound II;

[0046] H3: Compound II, Compound III, and acetate were added to acetic anhydride, stirred at a certain temperature, and treated with an organic solvent to obtain Compound I;

[0047] Compound V includes

[0048] Compound VI includes

[0049] Compound II includes

[0050] Compound III is One of them;

[0051] R1 is

[0052] Furthermore, the temperature for heating in step H1 is 30-50°C;

[0053] Preferably, the protective gas in step H2 includes one of argon and nitrogen, and more preferably, the protective gas is argon;

[0054] Preferably, the solvent in step H2 is tetrahydrofuran;

[0055] Preferably, the heating temperature in step H2 is 50-70°C;

[0056] Preferably, the acid solution in step H2 is a dilute hydrochloric acid solution;

[0057] Preferably, the iodide in step H2 includes one of potassium iodide and sodium iodide;

[0058] Preferably, the acetate in step H3 includes one of sodium acetate and potassium acetate;

[0059] Preferably, the temperature in step H3 is 30-50°C;

[0060] Preferably, the stirring time in step H3 is 4-6 hours.

[0061] A method for preparing nanoparticles of polymethyl cyanine molecules with long absorption wavelengths, wherein the compound is prepared into compound nanoparticles.

[0062] The preparation of compound nanoparticles includes:

[0063] Add DSPE-PEG-2000 and compound I to an organic solvent, mix thoroughly, evaporate the solution to dryness, add PBS buffer, and sonicate.

[0064] A method for preparing long-absorption wavelength polymethyl cyanine molecules is applied in the preparation of antitumor drugs;

[0065] The nanoparticles of this compound can generate heat when exposed to light, thereby inhibiting the growth of tumor cells.

[0066] Preferably, the tumor cells include one or more selected from colorectal cancer cells, breast cancer cells, lung cancer cells, gastric cancer cells, liver cancer cells, human placental choriocarcinoma cells, and cervical cancer cells;

[0067] The long-absorption wavelength polymethyl cyanine molecule, its preparation method, and its application described in this invention have the following advantages:

[0068] This invention achieves the design and synthesis of a high-performance NIR-II photothermal absorber by increasing the conjugated structure of molecules to reduce the molecular band gap and thus increasing nonradiative transitions. Cyanide molecules are composed of indole salt molecules connected at both ends by a conjugated ethylene structure. These molecules possess high molar absorption coefficients and near-infrared II absorption capabilities, and their good biocompatibility and low toxicity make them widely used in many research fields. The compound in this application has an absorption wavelength exceeding 1200 nm and a photothermal conversion efficiency of 82.3%. Attached Figure Description

[0069] The accompanying drawings, which constitute a part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0070] Figure 1 The molecular structures and ultraviolet fluorescence wavelength diagrams of IC-790, IC-830, IC-1030, IC-1060, IC-1080 and IC-1224 described in the embodiments of the present invention are shown in Figure A (Molecular structure diagram, Ultraviolet fluorescence wavelength diagram).

[0071] Figure 2 This is a schematic diagram illustrating the theoretical calculations of the HOMO and LUMO energy levels of IC-790, IC-830, IC-1030, IC-1060, IC-1080, and IC-1224 as described in the embodiments of the present invention.

[0072] Figure 3 The following is a flowchart of the preparation process and performance testing diagram of the water-soluble nanoparticles (IC-1224-NPs) of Example 6 of the present invention (A is a diagram of the preparation of IC-1224 water-soluble nanoparticles, B is a TEM image of IC-1224-NPs with a scale bar of 300 nm; C is a particle size distribution diagram of IC-1224-NPs with an average diameter of 202 nm measured by dynamic light scattering, D is a UV absorption spectrum of IC-1224-NPs in PBS, and E is a fluorescence absorption spectrum of IC-1224-NPs in PBS).

[0073] Figure 4 The following is a diagram of the photothermal performance test of IC-1224-NPs in Example 6 of this invention: (A is a schematic diagram of the photothermal characteristic test; B is a graph showing the relationship between the temperature rise of IC-1224-NP in water and the power density (1064nm); C is a graph showing the relationship between the temperature rise of IC-1224-NP in water and the concentration (1064nm, 0.75W cm⁻¹)). -2 D represents the IC-1224-NPs solution at a power intensity of 0.75 W / cm². -2Photothermal image after 1 minute of 1064nm laser irradiation; E represents IC-1224-NP after five irradiation / cooling cycles (0.75W cm⁻¹). -2 The temperature variation graph within the range is shown, where F represents the temperature variation of IC-1224-NPs under a 1064nm laser (0.75W cm⁻¹). -2 The photothermal effect in the irradiated aqueous solution, where G is the negative natural logarithm of the cooling time and the temperature gained from the cooling period;

[0074] Figure 5 The diagram shows the in vitro cytotoxicity analysis of the compound (A is a schematic diagram of the cytotoxicity test, B and C are the results under darkness and light irradiation (1064 nm, 0.75 W cm⁻¹). -2 Cell viability images of 4T1 cells incubated with different concentrations of IC-1224-NPs after 5 minutes (D) are shown. D represents co-staining fluorescence imaging of 4T1 cells with calcein AM (green) and propidium iodide (red) after different treatments. Image showing cell illumination after incubation with IC-1224-NPs (0.05 mM) at 1064 nm and 0.75 W cm⁻¹. -2 (5 minutes) (scale bar is 50μm);

[0075] Figure 6 The diagram shows in vivo antitumor therapy (A is a schematic diagram of in vivo phototherapy, B is a diagram of a subcutaneous tumor model at different time points (0.2mM, 200μL, 0.50W cm⁻¹) after intravenous injection of IC-1224-NPs). -2 In vivo fluorescence imaging high-pass filter (1000 nm), C represents the temperature change curves of 4T1 tumors in mice treated with saline + light and IC-1224-NPs + light, respectively; D represents the temperature change curves of IC-1224-NPs and saline at 0.75-5.0 W / cm². -2 Thermal infrared images of 4T1 tumor-bearing mice after 5 minutes of (1064nm) laser irradiation (6 hours after injection), E: tumor photographs of each group 15 days after treatment, F: average tumor weight 15 days after treatment, G: changes in tumor volume in each group during treatment, H: changes in body weight of mice during different treatment periods, I: histological H&E analysis of tumor tissues collected from mice in different groups at the end of treatment (scale bar: 50μm). Detailed Implementation

[0076] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0077] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0078] Example 1

[0079] IC-790 synthesis roadmap:

[0080]

[0081] A-1: Under an argon atmosphere, 2,3,3-trimethylindole (1.0 g, 6.28 mmol, 1.0 eq) and 1-iodohexadecane (2.65 g, 7.53 mmol, 1.2 eq) were dissolved in chloroform (20 mL), and the reaction mixture was heated at 80 °C for 50 h. After the reaction was complete, the solid was collected and dried under vacuum to obtain gray solid A-1 (1.8 g, 56.0%), which could be used for the next step without further purification.

[0082] IC-790: In a 50 mL three-necked flask, A-1 (0.51 g, 1.0 mM, 1.0 eq), 2-chloro-3-(hydroxymethylene)-1-cyclohexene-1-carboxaldehyde (0.168 g, 0.05 mM, 0.5 eq), and sodium acetate (0.164 g, 2.0 mmol, 2.0 equiv) were added, followed by acetic anhydride (10 mL). The mixture was stirred at 65 °C for 5 h, and then the reaction solution was poured into diethyl ether to precipitate a solid. The solid was collected and purified by column chromatography (dichloromethane / methanol = 2 / 1) to obtain a green solid IC-790 (0.5 g, 48.5%).

[0083] Example 2

[0084] IC-830 synthesis roadmap:

[0085]

[0086] B-1: Under an argon atmosphere, 1,1,2-trimethyl-1H-benzo[e]indole (1.0 g, 4.78 mmol, 1.0 eq) and 1-iodohexadecane (2.02 g, 5.73 mmol, 1.2 eq) were dissolved in chloroform (20 mL), and the reaction mixture was heated at 80 °C for 50 h. After the reaction was complete, the solid was collected and dried under vacuum to obtain gray solid B-1 (1.2 g, 44.7%), which could be used for the next step without further purification.

[0087] IC-830: B-1 (0.19 g, 0.34 mmol, 1.0 eq), 2-chloro-3-(hydroxymethylene)cyclohexyl-1-encarbaldehyde (0.03 g, 0.17 mmol, 0.5 eq), and sodium acetate (0.056 g, 0.68 mmol, 2.0 eq) from a 50 mL three-necked flask were added to acetic anhydride (10 mL). The mixture was stirred at 65 °C for 5 h. The reaction solution was then poured into diethyl ether, and a solid precipitated. The solid was purified by column chromatography (dichloromethane / methanol = 2 / 1) to give a green solid IC-830 (0.2 g, 52.3%).

[0088] Example 3

[0089] IC-1030 synthesis roadmap:

[0090]

[0091] C-1: In a 50 mL three-necked flask, 1,8-naphthoimide (0.5 g, 2.95 mmol, 1.0 eq), NaH (0.104 g, 2.5 mmol, 1.5 eq, 60%), and 15 mL of anhydrous DMF were added, and the mixture was reacted in an ice bath for 0.5 h. Then, 1-iodohexadecane (2.46 g, 3.54 mmol, 1.2 eq) was added, and the mixture was reacted in an ice bath for 0.5 h, followed by heating to 40 °C and reacting for 4 h. The solvent was evaporated under vacuum, and the residue was purified by column chromatography (n-hexane / ethyl acetate = 10 / 1) to give a yellow solid C-1 (0.75 g, 64.0%).

[0092] C-2: Under argon atmosphere, C-1 (0.50 g, 1.3 mmol, 1.50 eq) and methylmagnesium chloride (3.0 M, 0.70 mL, 2.6 mmol, 2.00 eq) were added to anhydrous THF (10 mL), stirred at 60 °C for 1.5 h, then cooled, neutralized with 2 M hydrochloric acid, stirred for another 0.5 h, and then 5 mL of potassium iodide solution (1 M) was added. The solid was filtered and washed three times with deionized water to obtain the red C-2 product (0.55 g, 83%).

[0093] IC-1030: C-2 (0.519 g, 1.0 mmol, 1.0 eq), 2-chloro-3-(hydroxymethylene)cyclohexyl-1-enecarbaldehyde (0.085 g, 0.5 mmol, 0.5 eq), and sodium acetate (0.16 g, 2.0 mmol, 2.0 eq) from a 50 mL three-necked flask were added to acetic anhydride (10 mL). The mixture was stirred at 40 °C for 5 h. The reaction solution was then poured into diethyl ether, and a solid precipitated. The solid was collected and purified by column chromatography (dichloromethane / methanol = 2 / 1) to obtain the green solid IC-1030 (0.435 g, 41.5%).

[0094] Example 4

[0095] IC-1060 synthesis roadmap:

[0096]

[0097] D-1: In a 50 mL three-necked flask, 2-bromobenzaldehyde (0.465 g, 2.5 mmol, 1.0 eq), 2-indolone (0.53 g, 3.9 mmol, 1.5 eq), and cesium carbonate (2.2 g, 6.7 mmol, 2.6 eq) were added to 15 mL of dimethyl sulfoxide. The reaction was carried out at 120 °C for 4 h under nitrogen protection. After the reaction was complete, the solution was cooled to room temperature. The product was extracted with ethyl acetate, washed with water, and dried over anhydrous sodium sulfate. After the solvent was evaporated, the product was purified by column chromatography (n-hexane / ethyl acetate = 1 / 1) to give a yellow solid D-1 (0.43 g, 77.3%).

[0098] D-2: In a 50 mL three-necked flask, D-1 (0.38 g, 1.7 mmol, 1.0 eq), NaH (0.104 g, 2.5 mmol, 1.5 eq, 60%), and 15 mL of anhydrous DMF were added, and the mixture was reacted in an ice bath for 0.5 h. Then, 1-iodohexadecane (0.732 g, 2 mmol, 1.2 eq) was added, and the mixture was reacted in an ice bath for 0.5 h, followed by heating to 40 °C and reacting for 4 h. After the solvent was evaporated, the mixture was purified by column chromatography (n-hexane / ethyl acetate = 10 / 1) to give a yellow solid D-2 (0.53 g, 67.7%).

[0099] D-3: Under argon protection, D-2 (0.5 g, 1.12 mmol, 1.0 eq) and methylmagnesium chloride (3.0 M solution, 0.70 mL, 2.6 mmol, 2.32 eq) were added to anhydrous THF (10 mL), and stirred at 60 °C for 1 h. Then, 5 mL of potassium iodide solution (1 M) was added. The solid was filtered and washed three times with deionized water. A red product, D-3 (0.39 g, 60.7%), was obtained.

[0100] IC-1060: A solution of D-3 (0.57 g, 1.0 mmol, 1.0 eq), 2-chloro-3-(hydroxymethylene)cyclohexyl-1-encarbaldehyde (0.08 g, 0.5 mmol, 0.5 eq), and sodium acetate (0.164 g, 2.0 mmol, 2.0 eq) in acetic anhydride (10 mL) was stirred at room temperature for 4 hours, then treated with diethyl ether (60 mL). The solution was purified by column chromatography (dichloromethane / methanol = 2 / 1) to give IC-1060 solid (0.63 g, 54.9%).

[0101] Example 5

[0102] IC-1080 synthesis roadmap:

[0103]

[0104] E-1: In a 50 mL three-necked flask, add 0.59 g (2.5 mmol, 1.0 eq) of 3-bromonaphth-2-carboxaldehyde, 0.53 g (3.9 mmol, 1.5 eq) of 2-indolone, and 2.2 g (6.7 mmol, 2.6 eq) of cesium carbonate to 15 mL of dimethyl sulfoxide. The entire process is protected under argon atmosphere. After the reaction is complete, the solution is cooled to room temperature. The product is extracted with ethyl acetate, washed with water, and dried over anhydrous sodium sulfate. After the solvent is evaporated, the product is purified by column chromatography (n-hexane / ethyl acetate = 1 / 1) to give a yellow solid E-1 (0.38 g, 60.2%).

[0105] E-2: In a 50 mL three-necked flask, E-1 (0.37 g, 1.37 mmol, 1.0 eq), NaH (0.82 g, 2.0 mmol, 1.5 eq, 60%), and 15 mL of anhydrous DMF were added, and the mixture was reacted in an ice bath for 0.5 h. Then, 1-iodohexadecane (0.732 g, 2 mmol, 1.2 eq) was added, and the mixture was reacted in an ice bath for 0.5 h, followed by a reaction at 40 °C for 4 h. After the solvent was evaporated, the mixture was purified by column chromatography (n-hexane / ethyl acetate = 10 / 1) to give a yellow solid E-2 (0.38 g, 56.0%).

[0106] E-3: Under argon atmosphere, E-2 (0.493 g, 1.0 mmol, 1.0 eq) and methylmagnesium chloride (3.0 M solution, 0.63 mL, 2.0 mmol, 2.0 eq) were added to anhydrous THF (10 mL), stirred at 60 °C for 1.5 h, then cooled, neutralized with 2 M hydrochloric acid, and stirred for another 0.5 h. The solid was filtered and washed three times with deionized water to obtain the red E-3 product (0.43 g, 69.4%).

[0107] IC-1080: E-3 (0.61 g, 1.0 mmol, 1.0 eq), 2-chloro-3-(hydroxymethylene)cyclohexyl-1-enecarbaldehyde (0.086 g, 0.5 mmol, 0.5 eq), and sodium acetate (0.164 g, 2 mmol, 2.0 eq) were added to acetic anhydride (10 mL), and the solution was stirred at room temperature for 4 h, then treated with diethyl ether (60 mL). The solution was purified by column chromatography (dichloromethane / methanol = 2 / 1) to obtain IC-1080 solid (0.58 g, 46.4%).

[0108] Example 6

[0109] IC-1224 synthesis route map:

[0110]

[0111] D-1: Take a 50 mL three-necked flask and add 2-bromobenzaldehyde (0.465 g, 2.5 mmol, 1.0 eq), 2-indolone (0.53 g, 3.9 mmol, 1.5 eq), and cesium carbonate (2.2 g, 6.7 mmol, 2.6 eq) to 15 mL of dimethyl sulfoxide. Under nitrogen protection, after the reaction is complete, cool the solution to room temperature. Extract the product with ethyl acetate, wash with water, and dry with anhydrous sodium sulfate. After the solvent is evaporated, purify by column chromatography (n-hexane / ethyl acetate = 1 / 1) to give yellow solid D-1 (0.43 g, 77.3%).

[0112] D-2: D-1 (0.38 g, 1.7 mmol, 1.0 eq), NaH (0.104 g, 2.5 mmol, 1.5 eq, 60%), and 15 mL of anhydrous DMF were added to a 50 mL three-necked flask and reacted in an ice bath for 0.5 h. Then, 1-iodohexadecane (0.732 g, 2 mmol, 1.2 eq) was added and reacted in an ice bath for 0.5 h, followed by heating to 40 °C and reacting for 4 h. After the solvent was evaporated, the mixture was purified by column chromatography (n-hexane / ethyl acetate = 10 / 1) to give a yellow solid D-2 (0.53 g, 67.7%).

[0113] D-3: Under argon protection, D-2 (0.5 g, 1.12 mmol, 1.0 eq) and methylmagnesium chloride (3.0 M solution, 0.70 mL, 2.6 mmol, 2.32 eq) were added to anhydrous THF (10 mL), and stirred at 60 °C for 1 h. Then, 5 mL of potassium iodide solution (1 M) was added. The solid was filtered and washed three times with deionized water. A red product, D-3 (0.39 g, 60.7%), was obtained.

[0114] IC-1224: A solution of D-3 (0.50 g, 0.87 mmol, 1.0 eq), F-1 (0.113 g, 0.5 mmol, 0.5 eq), and sodium acetate (0.145 g, 2 mmol, 2.0 eq) in acetic anhydride (10 mL) was stirred at room temperature for 4 h, and then treated with diethyl ether (60 mL). The solution was purified by column chromatography (dichloromethane / methanol = 2 / 1) to give IC-1224 solid (0.45 g, 41.5%).

[0115] like Figure 1 As shown, the ultraviolet fluorescence wavelengths of six near-infrared II hemisine fluorescent molecules, IC-790, IC-830, IC-1030, IC-1060, IC-1080, and IC-1224, from Examples 1 to 6, were measured. The experimental results show that among the synthesized molecules, IC-1224 has an absorption wavelength exceeding 1200 nm.

[0116] like Figure 2As shown, the calculated band gaps for molecules IC-790, IC-830, IC-1030, IC-1060, IC-1080, and IC-1224 are 1.946 eV, 1.875 eV, 1.529 eV, 1.559 eV, 1.524 eV, and 1.241 eV, respectively. Figure 2 The results show that the band gaps of IC-790 and IC-830 are relatively small, as are those of IC-1030, IC-1060, and IC-1080; these differences are negligible. However, the band gaps of IC-790, IC-1060, and IC-1224 are significantly different, a result consistent with the aforementioned spectral measurements. This further demonstrates that only by adding conjugated structures at appropriate positions within the molecule can the band gap be effectively reduced, resulting in a significant redshift of the molecular wavelength. The band gap values ​​in the four near-infrared II regions are lower than those of previously reported photothermal molecules, and the nonradiative decay rate typically increases exponentially with decreasing band gap. Therefore, a small HOMO-LOMO band gap can promote the photothermal effect of molecules.

[0117] Example 7

[0118] 10 mg of DSPE-PEG-2000 and 1 mg of compound IC-1224 (the compound prepared in Example 6) were dissolved in 1.0 mL of chloroform, the solution was evaporated to dryness, 1 mL of 1×PBS was added and mixed, and the mixture was sonicated for 10 min to obtain compound nanoparticles.

[0119] IC-1224 water-soluble nanoparticles (IC-1224-NPs) were fabricated using the DSPE-PEG-2000 nanoprecipitation method. Figure 3 A). In this process, hydrophobic molecules randomly aggregate in the core, while hydrophilic PEG chains form a shell, resulting in water-soluble nanoparticles that are better suited for use in living organisms. To characterize the size and morphology of the nanoparticles, we used dynamic light scattering (DLS) and transmission electron microscopy (TEM). TEM images show that IC-1224-NPs have a spherical morphology with an average diameter of 90–110 nm. Figure 3 B). Furthermore, DLS indicates that the hydrodynamic diameter of IC-1224-NPs is 202 nm ( Figure 3C). The small size obtained by TEM measurement is likely due to the shrinkage of the hydration layer in the dried TEM sample. Nanoparticles with diameters of 10–200 nm can aggregate at tumor sites due to the high permeability and retention effect (EPR) of solid tumors. Furthermore, polymer nanoparticles with PEG shells are promising nanocarriers due to their good stability during blood circulation. Therefore, these nanoparticles with PEG shells and suitable sizes (≈200 nm) are well-suited for in vivo cancer tumor therapy. The obtained IC-1224-NPs were well dispersed in aqueous solution with good transparency. We tested their UV absorption and fluorescence (…). Figure 3 D、 Figure 3 E), IC-1224-NPs have two absorption peaks concentrated at 920 nm and 1040 nm, respectively. The ultraviolet absorption peak of the nanoparticles of this molecule shows a blue shift compared to the molecule itself, which is attributed to their planar structure, leading to H aggregation of the molecules during nanoparticle preparation. However, the nanoparticles exhibit strong absorption at 1060 nm.

[0120] In addition, quantum yield is also an important parameter for measuring the optical performance of molecules. Using IR-26 as a reference, we calculated the quantum yield of IC-1224-NPs to be 0.005%. This quantum yield is very low, indicating that the radiative transitions of the molecule are very weak after it is encapsulated. This ensures its high photothermal conversion capability.

[0121] Molecular photothermal properties

[0122] IC-1224-NPs were irradiated with a 1064nm laser to investigate their photothermal conversion capability in water. Figure 4 A). First, relevant tests were conducted on the concentration of nanoparticles and the power of the laser. Figure 4 B Figure 4 C) The results showed that the laser power was 0.75 W / cm² when the nanoparticle concentration was 30 μM. -2 The optimal time was determined. Furthermore, the photothermal effect was positively correlated with the IC-1060-NPs concentration, laser exposure power, and time, indicating that heat generation could be well controlled. Therefore, we used a 1064nm laser with a power of 0.75 W / cm². -2 Laser irradiation of a 30 μM IC-1224-NPs solution significantly increased the solution temperature by approximately 24 °C within 1 minute. Figure 4 D). The significant temperature rise clearly demonstrates the efficient photothermal effect of IC-1224-NPs. Notably, IC-1224-NPs exhibit excellent thermal stability, showing no degradation after five cycles of heating and cooling under continuous laser irradiation. Figure 4E). Furthermore, PCE is a very important parameter for evaluating the photothermal properties of molecules. Therefore, at 0.75 W cm⁻¹ -2 The temperature change of a nanoparticle solution was measured under laser irradiation. The laser was turned off when the solution reached its maximum temperature after continuous irradiation. Based on the cooling stages of the solution, a negative natural logarithmic curve of cooling time (t) versus temperature driving force (-lnθ) was obtained. Figure 4 Based on the obtained data, the photothermal conversion efficiency of IC-1224-NPs was finally calculated to be 83.2% (F). Figure 4 G). The PCE of these IC-1224-NPs is higher than that of most previously reported photothermal agents.

[0123] Cytotoxicity

[0124] The phototoxicity of IC-1224-NPs to 4T1 cancer cells was detected by MTT assay (3-(4,5-dimethylthiazolyl-2-yl)-2,5-diphenyltetrazolium bromide). Figure 5 A). The cytotoxicity of the nanoparticles against cancer cells was evaluated under both dark and light conditions. Even with high concentrations of nanoparticle solution, almost no cytotoxicity was observed under dark conditions, indicating that the nanoparticles have good biocompatibility. Figure 5 B). Conversely, using 0.75W cm -2 After 5 minutes of 1064 nm laser irradiation, cell viability decreased significantly with increasing nanoparticle solution concentration. The results indicate that light irradiation can trigger the photothermal effect of nanoparticles in cells, and that increasing the temperature is sufficient to effectively kill cancer cells. Figure 5 C). To more visually demonstrate the effectiveness of IC-1224-NPs photothermal therapy, we used calcein AM (green) and propidium iodide (red) staining for live and dead cells. Green fluorescence indicates live cells, and red indicates dead cells. As expected, confocal imaging showed that under laser irradiation (0.75W cm⁻¹), live and dead cells were effectively stained. -2 After 5 minutes, the 4T1 cells treated with nanoparticles showed obvious red fluorescence, indicating that the 4T1 cells were completely dead. Figure 5 G). However, only green fluorescence was observed in saline, light alone, and in the nanoparticle group alone. Figure 5 D、 Figure 5 E, Figure 5 F) indicates that strong cytotoxicity only occurs when nanoparticles and laser irradiation coexist. This has significant potential applications in the field of tumor treatment.

[0125] Internal phototherapy

[0126] The tumor PTT effect in tumor-bearing mice injected with IC-1224-NPs was investigated. Figure 6 A). To obtain the optimal time point for PTT (Pulse Tolerance), fluorescence images of the tumor site were recorded after intravenous injection of nanoparticles via the tail vein. The fluorescence signal at the tumor site increased in a time-dependent manner, reaching a stable intensity 6 hours after injection. Therefore, the nanoparticles exhibit a significant EPR (Effective Perception) effect, leading to effective accumulation in tumor tissue. Furthermore, the fluorescence signal helps guide the irradiation time and location during PTT. A significant decrease in fluorescence signal was observed 12 hours post-injection, indicating that the nanoparticles can be eliminated from the body after treatment. Figure 6 B). We use a safe laser intensity (0.75W cm⁻¹). -2 The irradiation study investigated the tumor-killing effect. In vivo photothermal imaging showed that the temperature of the laser group (saline + laser) remained almost unchanged. Figure 6 C Figure 6 D). Therefore, the power is 0.75W cm. -2 Continuous irradiation with a 1064nm laser did not cause tissue overheating, meeting the basic requirements for in vivo phototherapy. Conversely, tumors in the IC-1224-NPs and laser groups showed a rapid temperature increase of approximately 25°C, indicating that IC-1224-NPs exhibited good photothermal effects in vivo. The PTT effect in each group was assessed by monitoring tumor volume every three days for 15 days post-treatment. Treatment in the saline, IC-1224-NPs, and laser-only groups failed to inhibit tumor growth, with an average tumor volume increase of 4-5 times. The results indicate that an intensity of 0.75W / cm² is optimal. -2 Single laser irradiation at 1064 nm and IC-1224-NPs alone failed to inhibit tumor growth. However, in the IC-1224-NPs + laser group, tumors were inhibited and eliminated without recurrence. These findings are highly consistent with in vitro phototoxicity results, confirming that IC-1224-NPs exhibit excellent PTT (phototransfer-to-tumor) effects under laser irradiation. Figure 6 E, Figure 6 F, Figure 6 G, Figure 6 H). Histological hematoxylin and eosin (H&E) staining images of tumor tissue after treatment showed severe necrosis in the IC-1224-NPs+Light group, while cancer cells in other groups were unaffected. Figure 6(I) In addition, IC-1224-NPs also demonstrated excellent in vivo physiological safety. The body weight of all mice in both the control and experimental groups was unaffected, indicating that these treatments did not cause systemic toxicity in the mice. Furthermore, the toxicity of IC-1224-NPs was estimated by analyzing the tissues of the major organs (heart, liver, spleen, lungs, and kidneys) of mice euthanized after treatment. No pathological tissue damage was observed in any of these organs in all groups, demonstrating the good biocompatibility of IC-1224-NPs. These results confirm that IC-1224-NPs have a good PTT effect and do not cause in vivo systemic toxicity.

[0127] A series of polymethyl cyanine molecules with large conjugated structures were synthesized as novel organic NIR-II photothermal absorbers. Photophysical property studies and theoretical calculations show that the strong electronic effect caused by the large conjugated structure plays a key role in the redshift of its absorption band towards the NIR-II window. Furthermore, only by adding conjugated structures at appropriate positions within the molecule can the band gap be effectively reduced, resulting in a significant redshift of the absorption band. In addition, the long alkyl chain prevents intermolecular aggregation, allowing for some intermolecular movement when encapsulated in DSPE-PEG-2000. This may explain the photothermal conversion efficiency of IC-224-NPs at 83.2%. In vitro and in vivo experiments demonstrated that IC-1224-NPs exhibits good biocompatibility and excellent photothermal therapeutic effects by inhibiting the growth and metastasis of 4T1 and deep tumors in mice through the EPR effect. Based on the results of this study, we anticipate that this series of molecules and their well-defined analogues may have great potential as promising photothermal agents (PTAs) for clinical photothermal therapy. Short-wavelength compounds have poor penetration into living tissue, leading to poor photothermal therapeutic effects.

[0128] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polymethyl cyanine molecule with a long absorption wavelength, characterized in that: Compound I has the following structure: ； R1 is ; R2 is H; R4, R5 and R3 form a ring, wherein the ring is naphthalene.

2. The method for preparing a long-absorption wavelength polymethyl cyanine molecule according to claim 1, characterized in that: Includes the following steps: Compound II, Compound III, and acetate were added to acetic anhydride, stirred at a certain temperature, and treated with an organic solvent to obtain Compound I; Compound II is ; Compound III is ; R1 is ; R2 is H; R4, R5 and R3 form a ring, wherein the ring is naphthalene.

3. The method for preparing a long-absorption wavelength polymethyl cyanine molecule according to claim 2, characterized in that: The acetate is selected from sodium acetate or potassium acetate.

4. The method for preparing a long-absorption wavelength polymethyl cyanine molecule according to claim 2, characterized in that: The temperature is 30-50 ℃.

5. The method for preparing a long-absorption wavelength polymethyl cyanine molecule according to claim 2, characterized in that: The stirring time is 4-6 hours.

6. The method for preparing a long-absorption wavelength polymethyl cyanine molecule according to claim 2, characterized in that: The preparation method of compound I includes the following steps: G1: Under a protective atmosphere, compound IV and 1-iodohexadecane were dissolved in an organic solvent and heated to obtain compound II; G2: Compound II, Compound III, and acetate were added to acetic anhydride, stirred at a certain temperature, and treated with an organic solvent to obtain Compound I; Compound IV is selected from: ; Compound II is ; Compound III is ; R1 is .

7. The method for preparing a long-absorption wavelength polymethyl cyanine molecule according to claim 6, characterized in that: The protective gas in step G1 is selected from argon or nitrogen.

8. The method for preparing a long-absorption wavelength polymethyl cyanine molecule according to claim 6, characterized in that: The protective gas is argon.

9. The method for preparing a long-absorption wavelength polymethyl cyanine molecule according to claim 6, characterized in that: The organic solvent in step G1 is selected from chloroform.

10. The method for preparing a long-absorption wavelength polymethyl cyanine molecule according to claim 6, characterized in that: The heating temperature in step G1 is 60-100 ℃.

11. The method for preparing a long-absorption wavelength polymethyl cyanine molecule according to claim 6, characterized in that: The acetate in step G2 is selected from sodium acetate or potassium acetate.

12. The method for preparing a long-absorption wavelength polymethyl cyanine molecule according to claim 6, characterized in that: The temperature in step G2 is 30-50 ℃.

13. The method for preparing a long-absorption wavelength polymethyl cyanine molecule according to claim 6, characterized in that: The stirring time in step G2 is 4-6 hours.

14. The polymethyl cyanine molecule prepared by the method for preparing a long-absorption wavelength polymethyl cyanine molecule according to any one of claims 2-13, or the compound nanoparticles prepared by the polymethyl cyanine molecule with a long absorption wavelength according to claim 1, characterized in that: The preparation of compound nanoparticles includes: Add DSPE-PEG-2000 and compound I to an organic solvent, evaporate the solution to dryness, add PBS buffer and sonicate.

15. The application of the polymethyl cyanine molecule with a long absorption wavelength according to claim 1 or the polymethyl cyanine molecule with a long absorption wavelength according to any one of claims 2-13, characterized in that: It is used in the preparation of anti-tumor drugs, wherein the tumor cells are breast cancer cells.

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