A photosensitizer based on D1-π-A-π-D2 type structure of asymmetrically capped donor units

Abstract

This invention relates to a photosensitizer with a D1-π-A-π-D2 type structure based on asymmetric end-capped donor units. This material is characterized by using 4-(5-(4-(9H-carbazole-9-yl)phenyl)) as donor units (D1) and 5-(4-(diphenylamino)phenyl) as donor units (D2), with isooctylthiophene as the connecting π-bridge, and phenazine as the central acceptor unit (A), specifically naphthiazo[1,2-b][1,2,5]thiadiazo[3,4-g]quinoxaline and [1,2,5]thiadiazo[3,4-i]dithienozo[2,3-a:3',2'-c]phenazine. The photophysical properties of this D1-π-A-π-D2 type photosensitizer were tested, and a novel photosensitizer with high photothermal conversion efficiency and high reactive oxygen species (ROS) yield was developed. The material involved in this invention has near-infrared II region imaging and photothermal in-situ imaging diagnostic functions, and is expected to be used as an organic photosensitizer material for integrated photothermal and photodynamic diagnosis and treatment.

Description

Technical Field

[0001] This invention relates to the field of organic photosensitizers for photothermal and photodynamic therapy, and particularly to a photosensitizer based on a D1-π-A-π-D2 type structure of an asymmetric end-capped donor unit. Background Technology

[0002] With the rapid development of biomedicine, single-modality diagnostic and treatment methods are no longer sufficient to meet the extremely high requirements of precision medicine. Near-infrared II (NIR-II, 1000-1700 nm) fluorescence imaging has shown great potential in the field of in vivo imaging due to its deeper tissue penetration, higher spatial resolution, and lower autofluorescence. Meanwhile, the synergistic treatment of photothermal therapy (PTT) (ACS Biomater. Sci. Eng., 2016, 2, 1357) and photodynamic therapy (PDT) (Chem. Rev., 2010, 110, 2795) provides a new strategy for efficient and low-side-effect tumor eradication. However, efficiently integrating NIR-II imaging, photothermal in situ monitoring (PTI), and photothermal / photodynamic synergistic therapy functions into a single small molecule remains a significant challenge.

[0003] Leveraging the weak tissue scattering and deep penetration characteristics of photons in the near-infrared II region, high signal-to-noise ratio and high-resolution imaging of deep tissues becomes possible. Simultaneously, by introducing photothermal in-situ imaging capabilities into molecules, real-time and intuitive monitoring of temperature distribution in the laser-irradiated area allows for accurate tumor localization, avoiding overheating damage to normal tissues, and enabling visualization and controllability of the treatment process. Furthermore, PTT / PDT synergistic therapy can be achieved by designing molecular structures that can simultaneously and efficiently convert light energy into heat energy and generate reactive oxygen species (Dyes Pigments., 2019, 166, 189). This synergy effectively overcomes the limitations of single-therapy approaches and significantly improves tumor-killing efficiency. Summary of the Invention

[0004] To address the problems existing in the prior art, we have invented a photosensitizer based on D1-π-A-π-D2 type structures capped with 4-(5-(4-(9H-carbazole-9-yl)phenyl)) and 5-(4-(diphenylamino)phenyl). This material is characterized by using 4-(5-(4-(9H-carbazole-9-yl)phenyl)) as the donor unit (D1) and 5-(4-(diphenylamino)phenyl) as the donor unit (D2), with isooctylthiophene as the connecting π-bridge, and with naphthiadiazo[1,2-b][1,2,5]thiadiazo[3,4-g]quinoxaline and [1,2,5]thiadiazo[3,4-i]dithieno[2,3-a:3',2'-c]phenazine as the central acceptor unit (A). The photophysical properties of this D1-π-A-π-D2 type photosensitizer were tested, and a novel photosensitizer with a high molar absorption coefficient, a wide response absorption spectrum, and a suitable energy level was developed and designed.

[0005] Therefore, the purpose of this invention is to provide a novel photosensitizer with broad application prospects, which exhibits strong light-harvesting ability in photophysical testing. Nanoparticles made using this photosensitizer material, under illumination, demonstrate high photothermal performance, clear near-infrared II imaging capabilities and thermal imaging effects, as well as high ROS generation and low dark toxicity, showing great promise for integrated biomedical diagnostic and therapeutic applications.

[0006] Based on the classic DAD structure, this material introduces different triarylamine (D) units at the ends to form an asymmetric molecular structure D1-π-A-π-D2, aiming to achieve better photothermal and photodynamic therapy performance of the photosensitizer. The design and synthesis of the photosensitizers Asy-AP and Asy-T are pioneering achievements. These invented photosensitizers Asy-AP and Asy-T can be applied to photothermal and photodynamic therapy, generating a photothermal effect and producing reactive oxygen species under light irradiation. The molecular structure and intermediates of this D1-π-A-π-D2 type material can be any of the following molecules.

[0007]

[0008] Formula 1. Asy-AP

[0009] Formula 2. Asy-T The above-mentioned D1-π-A-π-D2 type photosensitizers include any of the following derivatives: Asy-AP is a D1-π-A-π-D2 type photosensitizer with 5-(4-(diphenylamino)phenyl) as the donor unit (D1) and 4-(5-(4-(9H-carbazole-9-yl)phenyl)) as the donor unit (D2), isooctylthiophene as the connecting π bridge, and naphthiadiazolo[3,4-g]quinoxaline as the electron-withdrawing central group (A).

[0010] Asy-T is a D1-π-A-π-D2 type photosensitizer with 5-(4-(diphenylamino)phenyl) as the donor unit (D1) and 4-(5-(4-(9H-carbazole-9-yl)phenyl)) as the donor unit (D2), isooctylthiophene as the connecting π bridge, and [1,2,5]thiadiazo[3,4-i]dithieno[2,3-a:3',2'-c]phenazine as the electron-withdrawing central group (A).

[0011] The following is the specific synthesis route (see attached diagram in the instruction manual). Figure 3 ): To obtain the above materials, the synthesis scheme of the present invention is as follows: Synthesis of D1-π-A-π-D2 type photosensitizer Asy-AP: Compound Asy-NH2 and o-diketone acenaphthene-1,2-dione undergo a dehydration condensation reaction under heating conditions and in the presence of acetic acid to synthesize photosensitizer Asy-AP.

[0012] Synthesis of D1-π-A-π-D2 type photosensitizer Asy-T: Compound Asy-NH2 and benzo[2,1-b:3,4-b']dithiophene-4,5-dione undergo a dehydration condensation reaction under heating conditions and in the presence of acetic acid to synthesize photosensitizer Asy-T.

[0013] Compared with most disclosed photosensitizers, the D1-π-A-π-D2 type photosensitizer of the present invention is characterized by: (1) the introduction of 5-(4-(diphenylamino)phenyl) as a donor unit (D1) and 4-(5-(4-(9H-carbazole-9-yl)phenyl)) as a donor unit (D2), which reduces the ACQ effect of the photosensitizer and reduces the luminescence quenching of the material while easily adjusting the solubility; (2) the introduction of isooctylthiophene as a bridging unit (π), which not only easily adjusts the solubility but also cleverly sets the direction of the side chain, reducing the ACQ effect of the photosensitizer and reducing the luminescence quenching of the material; (3) the presence of donor-acceptor interaction in the molecule forms a strong ICT interaction, broadens the spectral absorption range, and enhances the light-harvesting ability of the photosensitizer. Therefore, this type of material is a promising organic photosensitizer material for photothermal therapy and photodynamic therapy.

[0014] The application of this invention is as follows: the photosensitizer organic material designed in this invention is used to generate a photothermal effect and produce reactive oxygen species under light conditions. It can be used for photothermal therapy and photodynamic therapy on tumor sites and cancer cells, and has clear near-infrared II zone imaging function and thermal imaging effect, which can realize the integrated application of tumor diagnosis and treatment. Attached Figure Description

[0015] Figure 1 This is the molecular structural formula of the photosensitizer Asy-AP of the present invention; Figure 2 This is the molecular structural formula of the photosensitizer Asy-T of the present invention; Figure 3 The specific synthetic route of the photosensitizer of this invention is as follows; Figure 4 This is the UV-Vis absorption spectrum of the photosensitizer Asy-T in CCl4 according to the present invention; Figure 5 This is the fluorescence emission spectrum of the photosensitizer Asy-T nanoparticles of the present invention in water; Figure 6 This is a photothermal effect diagram of the Asy-T photosensitizer nanoparticles of the present invention under light irradiation; Figure 7 This is a photothermal imaging image of the Asy-T nanoparticles of this invention; Figure 8 This is a near-infrared image of a mouse tumor containing the Asy-T nanoparticles of this invention; Figure 9 This is a diagram illustrating the effect of Asy-T nanoparticles of the present invention generating reactive oxygen species (ROS). Figure 10 This is the innovative point of the molecular structure of the material in this invention. Detailed Implementation

[0016] The present invention will be further described below through specific embodiments, but these specific embodiments do not limit the scope of protection of the present invention in any way. Example 1

[0017] Synthesis of compound Asy-NO2 (see attached diagram in the specification) Figure 3 ): 4-(5-(7-(5-(4-(9H-carbazole-9-yl)phenyl)-3-(2-ethylhexyl)thiophen-2-yl)-5,6-dinitrobenzo[c][1,2,5]thiadiazole-4-yl)-4-(2-ethylhexyl)thiophen-2-yl)-N,N-diphenylamine (Asy-NO2).

[0018]

[0019] Under nitrogen protection, a 100 mL single-necked flask contained dinitrobenzothiadiazole (461 mg, 1.2 mmol), Cz-Sn (870 mg, 1.2 mmol), TPA-Sn (870 mg, 1.2 mmol), bis(triphenylphosphine) palladium dichloride (50 mg, 0.072 mmol), and dry toluene (30 mL). The reaction mixture was heated to 70°C. o The reaction was carried out overnight at C. After the reaction was stopped and cooled, the solvent was evaporated to dryness under reduced pressure, and the compound was purified by column chromatography using petroleum ether:dichloromethane (4:1) as the eluent. The compound was synthesized according to the general synthetic method. It should be noted that the two organotin compounds were added simultaneously, and the reaction was carried out overnight at 70°C. The solvents used were petroleum ether and dichloromethane (4 / 1, v / v) as the eluent, yielding Asy-NO2 as a deep purple solid (356 mg, yield 27%). 1 H NMR (500 MHz, CDCl3) δ / ppm 8.16(d, J = 7.8 Hz, 2H), 7.86 (t, J = 8.8 Hz, 2H), 7.68 – 7.60 (m, 2H), 7.53 – 7.41(m, 6H), 7.40 – 7.26 (m, 8H), 7.13 (d, J = 7.3 Hz, 4H), 7.07 (dd, J = 12.7, 8.0Hz, 4H), 2.51 – 2.39 (m, 4H), 1.04 – 0.99 (s, 18H), 0.90 – 0.75 (m, 12H). Example 2

[0020] Synthesis of compound Asy-NH2 (see attached diagram in the specification) Figure 3 ): 4-(5-(4-(9H-carbazole-9-yl)phenyl)))-3-(2-ethylhexyl)thiophen-2-yl)-7-(5-(4-(diphenylamino)phenyl))-3-(2-ethylhexyl)thiophen-2-yl)benzo[c][1,2,5]thiadiazole-5,6-diamine (Asy-NH2).

[0021]

[0022] Under nitrogen protection, a 100 mL single-necked flask contained Asy-NO2 (156 mg, 0.14 mmol), iron powder (78 mg, 1.4 mmol), and a solvent mixed in a chloroform / acetic acid mixture (1 / 1, volume ratio). The reaction mixture was heated to 80°C. o The reaction was carried out overnight. After the reaction was stopped and cooled, the solvent was evaporated to dryness under reduced pressure, and purified by column chromatography using petroleum ether: dichloromethane = 4:1 as the eluent. Asy-NH2 was a yellow solid product (140 mg, 95% yield). 1 H NMR (500 MHz, CDCl3) δ / ppm 8.16 (d, J = 7.5 Hz, 2H), 7.88 (d, J = 8.4 Hz, 2H), 7.61 (d, J = 7.5Hz, 2H), 7.53 – 7.40 (m, 7H), 7.34 – 7.27 (m, 5H), 7.18 – 7.00 (m, 10H), 3.30 (br, 4H), 2.46 – 2.31 (m, 4H), 1.26 – 0.96 (m, 18H), 0.87 – 0.65 (m, 12H). Example 3

[0023] Synthesis of compound Asy-AP (see attached diagram in the specification) Figure 3 ): 4-(5-(12-(5-(4-(9H-carbazol-9-yl)phenyl)-3-(2-ethylhexyl)thiophen-2-yl)naphthiazo[1,2-b][1,2,5]thiadiazo[3,4-g]quinoxaline-8-yl)-4-(2-ethylhexyl)thiophen-2-yl)-N,N-diphenylaniline (Asy-AP).

[0024]

[0025] Equimolar amounts of o-diamine Asy-NH2 (76 mg, 0.073 mmol) and o-diketane-1,2-dione (15 mg, 0.073 mmol) were mixed in a chloroform / acetic acid mixture (1 / 1, v / v) and heated with stirring at 80°C for 24 hours. After cooling to room temperature, the reaction mixture was poured into water and extracted three times with dichloromethane (50 mL × 3 each time). The combined organic layers were dried over anhydrous sodium sulfate and then concentrated under vacuum. The crude product was purified by silica gel column chromatography using petroleum ether and dichloromethane as eluents. The residue was purified by silica gel column chromatography with dichloromethane / petroleum ether (V / V, 1:2) as eluent to give a blue-purple solid Asy-AP (85 mg, 91% yield). 1 H NMR (400 MHz, CDCl3) δ / ppm 8.40 (dd, J = 6.9, 5.3 Hz, 2H), 8.16 (dd, J = 12.0, 8.4 Hz, 4H), 8.00 (d, J =8.4 Hz, 2H), 7.87 – 7.82 (m, 2H), 7.67 – 7.62 (m, 4H), 7.56 (s, 1H), 7.52 –7.43 (m, 4H), 7.39 (s, 1H), 7.34 – 7.28 (m, 5H), 7.19 – 7.09 (m, 7H), 7.05(t, J = 7.2 Hz, 2H), 2.52 (br, 4H), 1.26 (s, 2H), 1.03 – 0.84 (m, 16H), 0.58 –0.48 (m, 12H). 13 C NMR (151 MHz, CDCl3) δ / ppm 155.16, 153.47, 140.85, 139.66,136.73, 133.90, 131.58, 130.31, 129.90, 129.85, 129.35, 128.84, 127.45,127.11, 126.03, 124.52, 123.48, 123.08, 122.36, 120.38, 120.04, 109.90,40.35, 34.40, 32.63, 28.73, 25.72, 22.85, 14.01, 10.77. Example 4

[0026] Synthesis of compound Asy-T (see attached diagram in the specification) Figure 3 ): 4-(5-(12-(5-(4-(9H-carbazole-9-yl)phenyl)-3-(2-ethylhexyl)thiophen-2-yl)-[1,2,5]thiadiazo[3,4-i]dithiopheno[2,3-a:3',2'-c]phenazin-8-yl)-4-(2-ethylhexyl)thiophen-2-yl)-N,N-diphenylaniline (Asy-T).

[0027]

[0028] Equimolar amounts of o-diamine Asy-NH2 (144 mg, 0.1383 mmol) and benzo[2,1-b:3,4-b']dithiophene-4,5-dione (30 mg, 0.1383 mmol) were mixed in a chloroform / acetic acid mixture (1 / 1, v / v) and heated with stirring at 80°C for 24 hours. After cooling to room temperature, the reaction mixture was poured into water and extracted three times with dichloromethane (50 mL × 3 each time). The combined organic layers were dried over anhydrous sodium sulfate and then concentrated under vacuum. The crude product was purified by silica gel column chromatography using petroleum ether and dichloromethane as eluents to obtain a blue-purple solid, Asy-AP, by silica gel column chromatography using dichloromethane / petroleum ether (V / V, 1:2) as eluent. The residue was then purified to obtain a dark green solid, Asy-T (110 mg, 62% yield), by silica gel column chromatography using dichloromethane / petroleum ether (V / V, 1:3) as eluent. 1 H NMR (500 MHz, CDCl3) δ / ppm 8.19 (d, J = 7.8 Hz, 2H), 8.03 (d, J = 8.3 Hz, 2H), 7.85 (t, J = 4.6 Hz, 2H), 7.77 – 7.65 (m, 6H), 7.60 (s, 1H), 7.53 (d, J = 8.3 Hz, 2H), 7.45 (dd, J = 14.8, 7.2 Hz, 3H), 7.32 (t, J = 7.3 Hz, 6H), 7.19 (d, J = 7.8Hz, 6H), 7.09 (d, J= 7.2 Hz, 2H), 2.61 (br, 4H), 1.45 – 1.39 (m, 2H), 1.11 –0.82 (m, 16H), 0.56 – 0.44 (m, 12H). 13 C NMR (151 MHz, CDCl3) δ / ppm 152.78,147.60, 147.30, 145.95, 144.76, 144.59, 141.52, 140.73, 138.12, 138.01,136.75, 135.56, 135.43, 133.90, 132.55, 130.95, 129.36, 127.46, 127.09,126.68, 126.19, 125.90, 125.08, 124.54, 123.85, 123.65, 123.59, 123.34,123.08, 120.34, 119.94, 109.88, 40.49, 34.64, 32.58, 28.62, 25.68, 22.79, 13.96, 10.68. Example 5

[0029] Performance characterization of D-π-Ar type photosensitizers, testing of light absorption properties, photothermal properties, and cytotoxicity.

[0030] D-π-Ar type photosensitizers 1 H NMR spectra were measured using a Bruker Dex-400 NMR instrument, UV-Vis spectra were measured using a Shimadzu UV-2600 UV-Vis absorption spectrometer, fluorescence spectra were measured using an Edinburgh Instruments (FLS1000) fluorescence emission spectrometer, photothermal imaging was performed using a FLIR E60 thermal imager, and MTT cell viability was measured using a TECAN Infinite200 PRO microplate reader.

[0031] Example 6 The light absorption properties of photosensitizer Asy-T in carbon tetrachloride (CCl4) solution (see attached diagram in the instruction manual) Figure 4 ) from Figure 4 It can be seen that the main absorption peaks of Asy-T are at 459 nm and 696 nm, respectively, with the absorption peaks being close to the near-infrared region.

[0032] Example 7 The photosensitizer Asy-T nanoparticles are near-infrared II region emission spectra generated when the nanoparticles are dissolved in water and excited by a 660 nm laser (see attached diagram in the instruction manual). Figure 5 ) from Figure 5 It can be seen that the main emission peak of Asy-T nanoparticles in water is around 1009 nm, and its emission spectrum is red-shifted to the near-infrared II region. The emission at this wavelength has good biological tissue penetration, which is conducive to biological tissue imaging and provides conditions for near-infrared II region biological imaging.

[0033] Example 8 Photothermal effect of photosensitizer Asy-T nanoparticles under light irradiation (see attached diagram in the instruction manual) Figure 6 ) The spectrum shows that Asy-T nanoparticles, when excited by a 660 nm laser, have a strength of 0.3 W / m². -2 At high light intensity, with an illumination time of 300 seconds, the photothermal temperature reaches nearly 55°C. This high photothermal conversion efficiency is beneficial for eliminating tumor cells, achieving the goal of targeted photothermal therapy.

[0034] Example 9 Photothermal imaging of photosensitizer Asy-T nanoparticles (see attached diagram in the instruction manual) Figure 7 ) Figure 7 This image shows the photothermal bioimaging effect produced when Asy-T nanoparticles are intravenously injected into mice under excitation with 660 nm near-infrared light. The image represents Asy-T nanoparticles (Asy-T-NPs). From this spectrum, it can be determined that under 660 nm laser excitation, the wavelength of Asy-T nanoparticles is 0.3 W / m². -2 At high light intensity and with an illumination time of 300 seconds, the photothermal temperature at the tumor lesion reached nearly 45°C. This demonstrated good photothermal imaging performance, enabling photothermal bioimaging to assist in the diagnosis and treatment of lesions, and for in situ tumor imaging.

[0035] Example 10 Near-infrared imaging of mouse tumors with photosensitizer Asy-T (see attached image in the instruction manual) Figure 8 ) Figure 8 This study recorded near-infrared II bioimaging images of mice after intravenous injection of Asy-T nanoparticles at different time intervals, under excitation with 660 nm near-infrared light. The images show that, after intravenous injection of the photosensitizer, from 0 hours, 12 hours, 24 hours, to 36 hours, the clearest imaging of tumor lesions was achieved at 24 hours under 660 nm laser excitation. This demonstrates high-resolution near-infrared bioimaging, which can assist in the diagnosis and treatment of lesions through near-infrared tumor imaging.

[0036] Example 11 The effect of photosensitizer Asy-T nanoparticles generating reactive oxygen species (ROS) is illustrated in the attached diagram in the instruction manual. Figure 9 ) Figure 9 For Asy-T nanoparticles excited by a 660 nm laser, 0.3 W / m -2 The graph shows the concentration of reactive oxygen species (ROS) generated under light intensity and illumination time of 300 seconds. From this graph, it can be concluded that under near-infrared light excitation, with the addition of the ROS indicator DCFH (2',7'-dichlorodihydrofluorescein), DCFH is a sensitive ROS detection probe. As the ROS concentration increases, the fluorescence emission peak near 530 nm gradually strengthens. At 600 seconds, the fluorescence emission intensity reaches 3.25 × 10⁻⁶. 5 This indicates that the Asy-T nanoparticles have a high reactive oxygen species (ROS) photodynamic response effect. In in vitro tests, the Asy-T nanoparticles exhibited a high reactive oxygen species (ROS) photodynamic response effect, which is beneficial for disinfecting tumor cells and achieving the purpose of targeted photodynamic therapy (PDT).

[0037] Example 12 The innovative point of the molecular structure of the material in this invention (see attached figures in the specification) Figure 10 ) Although the invention has been described in conjunction with preferred embodiments, the invention is not limited to the above embodiments, and it should be understood that the appended claims summarize the scope of the invention. Guided by the inventive concept, those skilled in the art should recognize that any modifications made to the various embodiments of the invention will be covered by the spirit and scope of the claims.

Claims

1. A photosensitizer based on a D1-π-A-π-D2 type structure of asymmetric end-capped donor units, characterized in that, Its structural formula is shown in Formula I; ； Formula I. D1-π-A-π-D2 type photosensitizer.

2. The photosensitizer based on a D1-π-A-π-D2 type structure of asymmetric end-capped donor units according to claim 1, characterized in that, It is based on 4-(5-(4-(9H-carbazol-9-yl)phenyl)) as the donor unit (D1) and 5-(4-(diphenylamino)phenyl) as the donor unit (D2), with isooctylthiophene as the connecting π bridge, and with narf[1,2-b][1,2,5]thiadiazo[3,4-g]quinoxaline and [1,2,5]thiadiazo[3,4-i]dithieno[2,3-a:3',2'-c]phenazine as the central acceptor unit (A).

3. A photosensitizer based on a D1-π-A-π-D2 type structure of asymmetric end-capped donor units according to any one of claims 1 to 2, characterized in that, Under light conditions, it has a high ability to convert light into heat and generate reactive oxygen species, producing a synergistic therapeutic effect of light, heat and photodynamic therapy. The material involved in this invention has both near-infrared II imaging function and light-heat imaging diagnostic function. This type of material can be applied to therapeutic photosensitizer organic materials for the synergistic treatment of cancer cells with light, heat and photodynamic therapy.

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