Aza-Bodipy photothermal agent absorbing near-infrared region II, preparation method thereof, and application thereof

Abstract

The present invention provides an aza-Bodipy photothermal agent with near-infrared region II absorption, its preparation method and application, and belongs to the field of photothermal therapy technology. First, XA0 is synthesized by using the Aldol / Dehydration reaction, and then XA1 is prepared by the Michael addition reaction. Subsequently, XA1 is used as a reaction intermediate and a condensation reaction is used to generate XA2. Finally, XA2 is reacted as a reactant with boron trifluoride monoethyl ether to obtain a near-infrared region II absorption photothermal agent XA3 with self-assembly ability. The photothermal agent obtained by the above preparation method has high solution stability and good photothermal activity under NIR-Ⅱ laser (1064nm) irradiation, and can be used for photothermal therapy of in situ tumors.

Description

Technical Field

[0001] The present invention belongs to the technical field of photothermal therapy, and specifically relates to an aza-Bodipy photothermal agent absorbing in the second near-infrared region, and a preparation method and application thereof. Background Art

[0002] Photothermal therapy (PTT) is a non-invasive cancer treatment method. Compared with clinical radiotherapy, chemotherapy and surgical treatment methods, it has the advantages of high temporal and spatial selectivity, short treatment time and low toxic side effects. Common PTT is mainly composed of a photothermal agent and a light source of a specific wavelength. The properties of the photothermal agent (such as photothermal conversion efficiency and light absorption wavelength) directly affect the treatment effect. However, the light absorption wavelengths of the photothermal agents with PTT potential are mainly concentrated in the near-infrared first region (Nar-infrared first region, NIR-Ⅰ). Because the photothermal agents absorbing in the near-infrared first region face the problems of shallow tissue penetration depth and low maximum safe light power density (≤0.33W / cm 2 ) and severe tissue photodamage, which greatly affect the efficacy of photothermal therapy and reduce its safety. Currently, organic photothermal agents in the near-infrared region II often need to increase the degree of conjugation to extend their absorption wavelength, resulting in high molecular weight and poor water solubility. In addition, they (such as polymethine cyanine dyes) have poor photo / thermal stability. Inorganic photothermal agents in the near-infrared region II also face problems such as poor biocompatibility, low photothermal conversion efficiency, and poor reproducibility.

[0003] Therefore, there is an urgent need to develop new near-infrared II photothermal agents to achieve near-infrared II (NIR-Ⅱ, >1000nm) absorption of photothermal agents and apply them to cancer photothermal therapy. Summary of the Invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide an aza-Bodipy photothermal agent with near-infrared region II absorption, as well as its preparation method and application, to solve the technical problems of existing near-infrared region II inorganic photothermal agents, such as high molecular weight and poor water solubility, poor light / thermal stability, poor biocompatibility, low photothermal conversion efficiency, and poor repeatability.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides an aza-Bodipy photothermal agent that absorbs in the second near-infrared region. The structural formula of the photothermal agent is as follows:

[0007]

[0008] The present invention also provides a method for preparing the aza-Bodipy photothermal agent having near-infrared second region absorption, comprising the following steps:

[0009] S1: Sodium hydroxide or potassium hydroxide and ethanol are added to julolidine aldehyde and 4-acetylpyridine, and the mixture is mixed uniformly to perform an aldol / dehydration reaction to obtain intermediate product I. Intermediate product I is added to a saturated sodium chloride aqueous solution to terminate the reaction, followed by extraction, drying, filtration, rotary evaporation, and purification to obtain XA0;

[0010] S2: XA0, nitromethane, ethanol, and sodium hydroxide are uniformly mixed, and the mixture is heated to a first set temperature and refluxed to perform a Michael addition reaction to obtain an intermediate product II. The intermediate product II is added to a saturated sodium chloride aqueous solution to terminate the reaction, followed by extraction, drying, filtration, rotary evaporation, and purification to obtain XA1;

[0011] S3: Evenly mix XA1, ethanol, and ammonium acetate, heat to a second set temperature, reflux for condensation reaction, cool to room temperature, filter, and wash to obtain XA2;

[0012] S4: Add XA2, anhydrous dichloromethane and diisopropylethylamine to boron trifluoride monoethyl ether, react at room temperature, and track the reaction on a plate. After the reaction is complete, extract, dry, filter, remove the solvent and perform column chromatography to obtain the photothermal agent XA3.

[0013] In the specific implementation process, the self-assembly step of the photothermal agent is also included:

[0014] Dissolve the photothermal agent XA3 in DSPE-PEG 5000 The nanostructured photothermal agent XA3@NPs was obtained by ultrasonic dissolution and then standing at a set speed.

[0015] In a specific implementation process, in S1, the molar ratio of julolidine aldehyde to 4-acetylpyridine is 1:1.

[0016] In a specific implementation process, in S2, the first set temperature is 85-95°C; the volume ratio of nitromethane, ethanol and sodium hydroxide is 1:20:5.

[0017] In a specific implementation process, in S3, the molar ratio of XA1 to ammonium acetate is 2.7:135; and the second set temperature is 110-120°C.

[0018] In a specific implementation process, in S4, the molar ratio of XA2, diisopropylethylamine and boron trifluoride monoethyl ether is 1:(1-2):(1.5-2.5).

[0019] In a specific implementation process, in S4, the column chromatography uses dichloromethane and methanol for separation and purification.

[0020] The present invention provides an application of the aza-Bodipy photothermal agent absorbing in the second near-infrared region in the preparation of photothermal therapy drugs.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention provides a method for preparing an aza-Bodipy photothermal agent with near-infrared region II absorption. The method uses inexpensive and readily available 4-acetylpyridine and julolidine aldehyde as starting materials. The electron-donating ability of the julolidine group and the electron-withdrawing ability of the pyridine group are utilized to construct XA3 with a push-pull electron effect, resulting in a red-shifted absorption wavelength. Furthermore, the rigidity of the julolidine and pyridine groups is utilized to form XA3 with good planarity, which facilitates its self-assembly ability. Furthermore, the nitrogen atoms in the julolidine and pyridine groups can serve as hydrogen bond acceptors during the self-assembly process, enhancing the self-assembly potential. By combining the push-pull electron effect with the dipole-dipole interaction during the self-assembly process, the low-molecular-weight XA3 possesses near-infrared region II absorption. Furthermore, according to the "energy gap law," the longer the absorption wavelength, the higher the non-radiative transition rate (internal conversion efficiency) of the molecule, and the better its photothermal performance. Therefore, the low-molecular-weight XA3 exhibits near-infrared region II photothermal conversion performance.

[0023] Furthermore, the aza-fluoroboron dipyrrole compound (aza-Bodipy) used has strong molecular rigidity and good planarity. In a biological water environment, it is easy to self-assemble (e.g., J aggregation) to achieve red-shifted absorption. Based on the synthesis of aza-fluoroboron dipyrrole complexes with near-infrared second-region absorption aza-Bodipy photothermal agents and their use in tumor treatment, it is theoretically feasible and has unique advantages. Therefore, the present invention designs and synthesizes a low-molecular-weight near-infrared second-region absorption aza-Bodipy photothermal agent, which has readily available raw materials, simple synthesis, low toxicity, deep tissue penetration, strong photothermal activity, and the like, and has the potential for photothermal treatment of deep-seated cancers.

[0024] The photothermal agent obtained by the above preparation method has high solution stability and good photothermal activity under NIR-Ⅱ laser (1064nm) irradiation. It can be used for photothermal treatment of in situ tumors, such as in situ osteosarcoma (Osteosarcoma), glioma (Glioma) and deep tumor photothermal treatment of lung tumors, and has bright application prospects.

[0025] The photothermal agent XA3 is simple and efficient to prepare, with low preparation cost and strong repeatability; it has strong rigidity, good planarity, and is easy to self-assemble, which makes the absorption wavelength red-shifted, such as Figure 1 、2 As shown; the near-infrared second region has strong absorption and high photothermal conversion efficiency, such as Figure 2 、 3 As shown; good biocompatibility, small toxic side effects, and outstanding photothermal treatment effects, such as Figure 4 , as shown in 5. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The thermal ellipsoid diagram of the crystal structure of XA3 of the present invention;

[0027] Figure 2 Figure (a) shows the absorption spectra of XA3 and XA3 of the present invention in a water / acetonitrile mixed solvent (water / acetonitrile); and Figure 2 The middle picture (b) shows the use of DSPE-PEG 5000 Normalized UV-visible-near-infrared absorption spectrum after coating;

[0028] Figure 3 The middle figure (a) is a temperature (heating and cooling) curve of the self-assembled photothermal agent XA3 of the present invention under 1064nm laser irradiation; Figure 3 The middle figure (b) shows the light / thermal stability test of the self-assembled photothermal agent XA3 under 1064nm laser irradiation;

[0029] Figure 4 This is a graph showing the XA3 cytotoxicity test of the self-assembled photothermal agent of the present invention;

[0030] Figure 5 This is a diagram evaluating the photothermal treatment effect of XA3 cells after the self-assembled photothermal agent of the present invention;

[0031] Figure 6 The structural formula of the photothermal agent XA3 of the present invention is:

[0032] Figure 7 Schematic diagram of the self-assembly of the photothermal agent XA3 of the present invention;

[0033] Figure 8 Schematic diagram of the preparation process of the photothermal agent XA3 of the present invention. DETAILED DESCRIPTION

[0034] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0035] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0036] Herein, all features such as values, amounts, amounts, and concentrations defined in numerical ranges or percentage ranges are for brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to include and specifically disclose all possible subranges and individual values ​​within the range (including integers and fractions).

[0037] In this document, unless otherwise specified, “include,” “including,” “contains,” “has” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0038] In this document, for the sake of brevity, not all possible combinations of the various technical features in each embodiment or example are described. Therefore, as long as there are no contradictions in the combination of these technical features, the various technical features in each embodiment or example can be combined in any way, and all possible combinations should be considered to be within the scope of this specification.

[0039] The present invention provides an aza-Bodipy photothermal agent capable of absorbing near-infrared light in the second region, a preparation method thereof, and an application thereof.

[0040] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0041] The following examples were prepared using conventional instruments and equipment in the art. Experimental methods in the following examples, where specific conditions are not specified, were generally performed under conventional conditions or according to the conditions recommended by the manufacturer. The various raw materials used in the following examples, unless otherwise specified, were conventional commercially available products, with specifications conventional in the art. In the present specification and the following examples, unless otherwise specified, "%" indicates percentage by weight, "part" indicates parts by weight, and "ratio" indicates weight ratio.

[0042] The present invention provides a method for preparing an aza-Bodipy photothermal agent with near-infrared second-region absorption. The method comprises the following steps: firstly, synthesizing XA0 by using an Aldol / Dehydration reaction, then preparing XA1 by a Michael addition reaction, then using XA1 as a reaction intermediate to generate XA2 by means of a condensation reaction, and finally reacting XA2 as a reactant with boron trifluoride monoethyl ether to obtain a near-infrared second-region absorption photothermal agent XA3 with self-assembly capability.

[0043] The specific steps are as follows:

[0044] Preparation of XA0: In a 250 mL round-bottom flask, add 4-acetylpyridine (e.g., 10 mmol), julolidine aldehyde (e.g., 10 mmol), ethanol (20 mL), and sodium hydroxide or potassium hydroxide (20%, 10 mL). Stir at room temperature for 24 h. Pour the reaction into saturated aqueous sodium chloride (10 mL) to quench the reaction, then extract with ethyl acetate (30 mL). Dry over anhydrous sodium sulfate and filter. Rotary evaporate and purify with a column (silica gel, EA) to obtain XA0 as a red solid. The molar ratio of julolidine aldehyde to 4-acetylpyridine is 1:1.

[0045] Preparation of XA1: In a 250 mL round-bottom flask, compound XA0 (3 mmol), nitromethane, ethanol, and sodium hydroxide (20%) were added and refluxed at 85-95°C for 24 h. The reaction was then quenched by pouring the mixture into saturated aqueous sodium chloride (10 mL) and extracted with ethyl acetate (30 mL). Anhydrous Na2SO4 was added, air-dried, and filtered. Purification by rotary evaporation on a silica gel column (EA) afforded XA1 as a light yellow solid. The volume ratio of nitromethane, ethanol, and sodium hydroxide was 1:20:5.

[0046] Preparation of XA2: In a 250 mL round-bottom flask, add compound XA1, ethanol (20 mL), and ammonium acetate. Reflux at 110-120°C for 24 hours. After cooling to room temperature, filter and wash three times with ethanol (20 mL) to obtain XA2 as a bluish-black solid. The molar ratio of XA1 to ammonium acetate is 2.7:135.

[0047] Preparation of XA3: Under N2 protection, compound XA2, 15 mL of anhydrous dichloromethane, and diisopropylethylamine were added sequentially to a 50 mL three-necked round-bottom flask. BF3·OEt2 was then slowly added. The reaction was allowed to proceed at room temperature for 24 h. After the reaction was complete, the mixture was poured into ice water and extracted. Anhydrous Na2SO4 was added and the mixture was dried overnight. The mixture was filtered, the solvent was removed by vortexing, and column chromatography (dichloromethane:methanol = 20:1) was performed to obtain a metallic solid XA3. The molar ratio of XA2, diisopropylethylamine, and boron trifluoride monoethyl ether was 1:(1-2):(1.5-2.5).

[0048] The present invention also provides an aza-Bodipy photothermal agent with near-infrared second-region absorption obtained by the above-mentioned preparation method. The structural formula of the photothermal agent is as follows:

[0049]

[0050] The self-assembly process of the near-infrared second-region absorbing photothermal agent XA3 is as follows: dissolving the photothermal agent XA3 in DSPE-PEG 5000 The nanostructured photothermal agent XA3@NPs was obtained by ultrasonic dissolution and then standing at a set speed.

[0051] The specific steps are as follows: 1 mg of XA3 and 10 mg of DSPE-PEG were weighed using an analytical balance. 5000 Place the solution in a clean centrifuge tube, add 1 mL of tetrahydrofuran, and stir for 1 hour. Once stirring is complete, quickly add the tetrahydrofuran solution to 10 mL of deionized water and sonicate for 10 minutes. After sonication, transfer the clarified solution to a magnetic stirrer and stir at 550 rpm at room temperature for 24 hours to remove the tetrahydrofuran. Finally, filter the solution through a 30K ultrafiltration tube and concentrate to obtain an aqueous solution of XA3@NPs.

[0052] A third aspect of the present invention provides the use of an aza-Bodipy photothermal agent with near-infrared II absorption in the preparation of a photothermal therapy drug. The photothermal agent obtained by this preparation method has high solution stability and good photothermal activity under NIR-II laser (1064 nm) irradiation. It can be used for photothermal therapy of in situ tumors, such as osteosarcoma, glioma, and deep-stage tumors such as lung tumors, and has a bright future.

[0053] Example 1

[0054] Preparation of XA0: To a 250 mL round-bottom flask, add 4-acetylpyridine (2.00 g, 10 mmol), julolidine aldehyde (2.00 g, 10 mmol), ethanol (20 mL), and sodium hydroxide (20%, 10 mL). Stir at room temperature for 24 h. Pour the reaction mixture into saturated aqueous sodium chloride (10 mL) to quench the reaction, then extract with ethyl acetate (30 mL). After drying over anhydrous sodium sulfate, the product was filtered. Rotary evaporation and purification by column chromatography (silica gel, EA) afforded XA0 (1.52 g) as a red solid in a 50% yield. 1HNMR (500MHz, CDCl3) δ / ppm=8.86–8.72(m,2H),7.87–7.68(m,3H),7.19–7.07(m,3H),3.36–3.27(m,4H),2.78(t,J=6.3Hz,4H),2.03–1.92(m,4H). 13 C NMR (126MHz, CDCl3) δ / ppm=189.4,150.5,148.3,145.9,145.9,128.7,121.6,121.1,121.0,114.6,50.0,27.7,21.4.HRMS(APCI + )[M+H + ] + :Calcd=305.1609; Found=305.1641.

[0055] Preparation of XA1: In a 250 mL round-bottom flask, compound XA0 (1.00 g, 3 mmol), nitromethane (1.00 mL), ethanol (20 mL), and sodium hydroxide (20%, 5.00 mL) were added and refluxed at 90°C for 24 h. The reaction was then quenched by pouring into saturated aqueous sodium chloride (10 mL) and extracted with ethyl acetate (30 mL). Anhydrous Na2SO4 was added, air-dried, and filtered. Purification by rotary evaporation on a silica gel column (EA) afforded XA1 (1.20 g) as a light yellow solid in a 90% yield. 1 H NMR (500MHz, CDCl3) δ / ppm=8.77(d,J=5.1Hz,2H),7.67(d,J=5.1Hz,2H),6.62(s,2H),4.64(ddd,J=44.0,12.3,7.3Hz, 2H), 3.70 (q, J = 7.0Hz, 1H), 3.38 (t, J = 7.3Hz, 2H), 3.09 (t, J = 5.6Hz, 4H), 2.68 (t, J = 6.5Hz, 4H), 1.92 (p, J = 6.2Hz, 4H). 13 C NMR (126MHz, CDCl3) δ / ppm=197.1,151.0,142.6,142.4,125.8,124.9,121.8,121.0,79.8,49.7,42.2,38.4,29.7,27.7,21.9.HRMS (APCI + )[M+H + ] + :Calcd=366.1773; Found=366.1803.

[0056] Preparation of XA2: In a 250 mL round-bottom flask, compound XA1 (1.00 g, 2.7 mmol), ethanol (20 mL), and ammonium acetate (10.45 g, 135 mmol) were added and refluxed at 115°C for 24 hours. After cooling to room temperature, the mixture was filtered and washed three times with ethanol (20 mL) to obtain XA2 as a blue-black solid (0.69 g) in a 70% yield. 1 H NMR (500MHz, CDCl3) δ / ppm=8.77(d,J=5.1Hz,4H),7.73(d,J=5.1Hz,4H),7.58(s,4H),7.05(s, 1H), 5.33 (d, J = 1.9Hz, 2H), 3.26 (d, J = 5.9Hz, 8H), 2.78 (d, J = 6.5Hz, 8H), 2.02 (d, J = 6.2Hz, 8H). 13 C NMR (126MHz, CDCl3) δ / ppm=152.3,150.6,144.5,143.4,139.6,128.2,121.2,112.0,111.7,50.2,31.6,27.9,22.7,22.0.HRMS (ESI + )[M+H + ] + :Calcd=642.3300; Found=642.3330.

[0057] Preparation of XA3: Under the protection of N2, compound XA2 (1 eq), 15 mL of anhydrous dichloromethane, and diisopropylethylamine (1.5 eq) were added to a 50 mL three-necked round-bottom flask in sequence, and BF3·OEt2 (1.5 eq) was slowly added. The reaction was carried out at room temperature for 24 h, and the reaction was tracked by plate. After the raw materials reacted completely, the mixture was poured into ice water, extracted, and dried overnight by adding anhydrous Na2SO4. The mixture was filtered, the solvent was removed by vortexing, and the metallic glossy solid XA3 was obtained by column chromatography (dichloromethane: methanol = 20:1). 1 H-NMR (500MHz, CDCl3) δ / ppm=8.72(d,J=5.4Hz,4H),7.88(d,J=6.0Hz,4H),7.65( s,4H),6.80(s,2H),3.38–3.33(m,8H),2.80(t,J=6.1Hz,8H),2.06–2.00(m,8H). 13 C-NMR (126MHz, CDCl3) δ / ppm=153.2,149.7,146.4,144.9,144.3,140.1,129.1,122.9,121.6,120.7,113.9,50.2,28.0,21.6.HRMS (ESI + )[M+H+ ] + :Calcd=690.3283; Found=690.3304.

[0058] Preparation of XA3@NPs: 1 mg of XA3 and 10 mg of DSPE-PEG were weighed using an analytical balance. 5000 Place the solution in a clean centrifuge tube, add 1 mL of tetrahydrofuran, and stir for 1 hour. Once stirring is complete, quickly add the tetrahydrofuran solution to 10 mL of deionized water and sonicate for 10 minutes. After sonication, transfer the clarified solution to a magnetic stirrer and stir at 550 rpm at room temperature for 24 hours to remove the tetrahydrofuran. Finally, filter the solution through a 30K ultrafiltration tube and concentrate to obtain an aqueous solution of XA3@NPs.

[0059] Example 2

[0060] Preparation of XA0: In a 250 mL round-bottom flask, add 4-acetylpyridine (2.00 g, 10 mmol), julolidine aldehyde (2.00 g, 10 mmol), ethanol (20 mL), and sodium hydroxide (20%, 10 mL). Stir at room temperature for 24 h. Pour the reaction into saturated aqueous sodium chloride (10 mL) to stop the reaction, then add ethyl acetate (30 mL) for extraction. After drying over anhydrous sodium sulfate, filter. Rotary evaporate and purify on a silica gel column (EA) to obtain XA0 as a red solid.

[0061] Preparation of XA1: In a 250 mL round-bottom flask, compound XA0 (1.00 g, 3 mmol), nitromethane (1.00 mL), ethanol (20 mL), and sodium hydroxide (20%, 5.00 mL) were added and refluxed at 85°C for 24 h. The reaction was then quenched by pouring into saturated aqueous sodium chloride (10 mL) and extracted with ethyl acetate (30 mL). After adding anhydrous NaSO, the mixture was air-dried and filtered. Purification by rotary evaporation on a silica gel column (EA) afforded XA1 as a light yellow solid.

[0062] Preparation of XA2: In a 250 mL round-bottom flask, add compound XA1 (1.00 g, 2.7 mmol), ethanol (20 mL), and ammonium acetate (10.45 g, 135 mmol). Reflux at 110°C for 24 hours. After cooling to room temperature, filter and wash three times with ethanol (20 mL) to obtain XA2 as a blue-black solid.

[0063] Preparation of XA3: Under the protection of N2, compound XA2 (1 eq), 15 mL of anhydrous dichloromethane, and diisopropylethylamine (2.0 eq) were added to a 50 mL three-necked round-bottom flask in sequence, and BF3·OEt2 (2.5 eq) was slowly added. The reaction was carried out at room temperature for 24 h, and the reaction was tracked by plate. After the raw materials reacted completely, the mixture was poured into ice water, extracted, and dried overnight by adding anhydrous Na2SO4. The mixture was filtered, the solvent was removed by vortexing, and the metallic glossy solid XA3 was obtained by column chromatography (dichloromethane: methanol = 20:1).

[0064] Preparation of XA3@NPs: 1 mg of XA3 and 10 mg of DSPE-PEG were weighed using an analytical balance. 5000 Place the solution in a clean centrifuge tube, add 1 mL of tetrahydrofuran, and stir for 1 hour. Once stirring is complete, quickly add the tetrahydrofuran solution to 10 mL of deionized water and sonicate for 10 minutes. After sonication, transfer the clarified solution to a magnetic stirrer and stir at 550 rpm at room temperature for 24 hours to remove the tetrahydrofuran. Finally, filter the solution through a 30K ultrafiltration tube and concentrate to obtain an aqueous solution of XA3@NPs.

[0065] Example 3

[0066] Preparation of XA0: In a 250 mL round-bottom flask, add 4-acetylpyridine (2.00 g, 10 mmol), julolidine aldehyde (2.00 g, 10 mmol), ethanol (20 mL), and sodium hydroxide (20%, 10 mL). Stir at room temperature for 24 h. Pour the reaction into saturated aqueous sodium chloride (10 mL) to stop the reaction, then add ethyl acetate (30 mL) for extraction. After drying over anhydrous sodium sulfate, filter. Rotary evaporate and purify on a silica gel column (EA) to obtain XA0 as a red solid.

[0067] Preparation of XA1: In a 250 mL round-bottom flask, compound XA0 (1.00 g, 3 mmol), nitromethane (1.00 mL), ethanol (20 mL), and sodium hydroxide (20%, 5.00 mL) were added and refluxed at 95°C for 24 h. The reaction was then quenched by pouring into saturated aqueous sodium chloride (10 mL) and extracted with ethyl acetate (30 mL). After adding anhydrous Na2SO4 and air-drying, the mixture was filtered. Purification by rotary evaporation on a silica gel column (EA) afforded XA1 as a light yellow solid.

[0068] Preparation of XA2: In a 250 mL round-bottom flask, add compound XA1 (1.00 g, 2.7 mmol), ethanol (20 mL), and ammonium acetate (10.45 g, 135 mmol). Reflux at 120°C for 24 hours. After cooling to room temperature, filter and wash three times with ethanol (20 mL) to obtain a blue-black solid XA2.

[0069] Preparation of XA3: Under the protection of N2, compound XA2 (1.0 eq), 15 mL of anhydrous dichloromethane, and diisopropylethylamine (1.0 eq) were added to a 50 mL three-necked round-bottom flask in sequence, and BF3·OEt2 (2.0 eq) was slowly added. The reaction was carried out at room temperature for 24 h, and the reaction was tracked by plate. After the raw materials reacted completely, the mixture was poured into ice water, extracted, and dried overnight by adding anhydrous Na2SO4. The mixture was filtered, the solvent was removed by vortexing, and the metallic glossy solid XA3 was obtained by column chromatography (dichloromethane: methanol = 20:1).

[0070] Preparation of XA3@NPs: 1 mg of XA3 and 10 mg of DSPE-PEG were weighed using an analytical balance. 5000 Place the solution in a clean centrifuge tube, add 1 mL of tetrahydrofuran, and stir for 1 hour. Once stirring is complete, quickly add the tetrahydrofuran solution to 10 mL of deionized water and sonicate for 10 minutes. After sonication, transfer the clarified solution to a magnetic stirrer and stir at 550 rpm at room temperature for 24 hours to remove the tetrahydrofuran. Finally, filter the solution through a 30K ultrafiltration tube and concentrate to obtain an aqueous solution of XA3@NPs.

[0071] like Figure 1 As shown in the figure, the CCDC number of the crystal is 2227219, indicating that the target photothermal agent XA3 has not been synthesized, and XA3 has strong rigidity and good planarity, and has the potential for self-assembly. Figure 2 As shown in (a), XA3 has the ability to self-assemble in water, which can make the absorption wavelength reach the near-infrared region. Figure 2 As shown in (b), XA3 was prepared in water / acetonitrile mixed solvent and DSPE-PEG 5000 The absorption spectra of XA3@NPs after coating are consistent, and the absorption can reach the near-infrared region II (>1000nm) and has strong near-infrared region II absorption, which further illustrates that the self-assembly of XA3 is universal.

[0072] like Figure 3 As shown in (a), through the heating and cooling curves, it can be calculated that XA3 has a good photothermal conversion efficiency (39.83%) under irradiation in the near-infrared region II (1064nm). Figure 3 As shown in (b), the self-assembled photothermal agent XA3 has high photothermal conversion efficiency and good photothermal stability, and can be used as a photothermal agent in near-infrared second-region photothermal therapy.

[0073] like Figure 4 As shown in the figure, the self-assembled photothermal agent XA3 has low dark cytotoxicity and good biocompatibility when not irradiated by 1064nm laser; however, under 1064nm irradiation, the cytotoxicity is significantly improved, indicating that the self-assembled photothermal agent XA3 can be used for further cell photothermal therapy. Figure 5 As shown, the green signal in the figure represents living cells, and the red signal represents apoptotic cells, which further illustrates that the self-assembled photothermal agent XA3 can be used for photothermal therapy in the near-infrared region II.

[0074] Performance Study:

[0075] Study on the photothermal conversion performance of the photothermal agent XA3 in the near-infrared second region of the present invention:

[0076] 1. The near-infrared region II light absorption performance of XA3 (10 μM) in solution and in self-packed state was tested by UV-visible-near-infrared spectrometer to evaluate its near-infrared region II light absorption capacity.

[0077] 2. Using an infrared thermal imager, the photothermal conversion ability of XA3 (0.2 mg / mL) was tested under near-infrared zone II laser irradiation (1064 nm) to evaluate its near-infrared zone II photothermal therapeutic potential.

[0078] The in vitro photothermal therapeutic efficacy of the photothermal agent XA3 of the present invention was studied using a Calcein-AM / PI staining kit to evaluate the efficiency of the complex XA3 in inducing cancer cell death under near-infrared laser irradiation (1064 nm). Calcein-AM can label the viability of living cells, emitting green fluorescence. Propidium iodide (PI) can penetrate disordered regions of dead cell membranes and reach the nucleus, where it binds to the DNA double helix and produces red fluorescence (λex = 535 nm, λem = 610-625 nm). The combination of Calcein-AM and PI allows for dual staining of live and dead cells, enabling qualitative analysis of the efficacy of XA3 photothermal therapy.

[0079] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. An aza-Bodipy photothermal agent absorbing in the second near-infrared region, characterized in that: The structural formula of the photothermal agent is as follows: 。 2. A method for preparing the aza-Bodipy photothermal agent with near-infrared second region absorption according to claim 1, characterized in that: The following steps are involved: S1: Sodium hydroxide or potassium hydroxide and ethanol are added to julolidine aldehyde and 4-acetylpyridine, and the mixture is uniformly mixed to perform an aldol / dehydration reaction to obtain intermediate product I. Intermediate product I is added to a saturated sodium chloride aqueous solution to terminate the reaction, followed by extraction, drying, filtration, rotary evaporation, and purification to obtain XA0. The structural formula of XA0 is as follows: ； S2: XA0, nitromethane, ethanol, and sodium hydroxide are uniformly mixed, and heated to a first set temperature and refluxed to perform a Michael addition reaction to obtain an intermediate product II. The intermediate product II is added to a saturated sodium chloride aqueous solution to terminate the reaction, followed by extraction, drying, filtration, rotary evaporation, and purification to obtain XA1. The structural formula of XA1 is as follows: ； S3: XA1, ethanol, and ammonium acetate are mixed uniformly, heated to a second set temperature, refluxed for condensation reaction, cooled to room temperature, filtered, and washed to obtain XA2; the structural formula of XA2 is as follows: ； S4: Add XA2, anhydrous dichloromethane and diisopropylethylamine to boron trifluoride monoethyl ether, react at room temperature, and track the reaction on a plate. After the reaction is complete, extract, dry, filter, remove the solvent and perform column chromatography to obtain the photothermal agent XA3.

3. The method for preparing the aza-Bodipy photothermal agent with near-infrared second region absorption according to claim 2, characterized in that: In the S1, the molar ratio of julolidine aldehyde to 4-acetylpyridine is 1:

1.

4. The method for preparing the aza-Bodipy photothermal agent with near-infrared second region absorption according to claim 2, characterized in that: In S2, the first set temperature is 85-95°C; the volume ratio of nitromethane, ethanol and sodium hydroxide is 1:20:

5.

5. The method for preparing the aza-Bodipy photothermal agent with near-infrared second region absorption according to claim 2, characterized in that: In S3, the molar ratio of XA1 to ammonium acetate is 2.7:135; and the second set temperature is 110-120°C.

6. The method for preparing the aza-Bodipy photothermal agent with near-infrared second region absorption according to claim 2, characterized in that: In S4, the molar ratio of XA2, diisopropylethylamine and boron trifluoride monoethyl ether is 1:(1-2):(1.5-2.5).

7. The method for preparing the aza-Bodipy photothermal agent with near-infrared second region absorption according to claim 2, characterized in that: In S4, the column chromatography uses dichloromethane and methanol for separation and purification.

8. Use of the aza-Bodipy photothermal agent with near-infrared second region absorption according to claim 1 in the preparation of photothermal therapy drugs.

Images