A near-infrared second-region aggregation-induced luminescence material and its preparation method and application

Abstract

The present invention discloses a highly efficient near-infrared zone II aggregation-induced luminescence material, a preparation method thereof, and its application in dual-modality surgical navigation. This type of molecular structure uses thionaphthalenetetracarboxylic acid diimide as an electron acceptor group and tetraphenylethylene as a molecular rotor and electron donor unit to construct an organic near-infrared zone II material with intramolecular charge transfer characteristics. By expanding the length of the π-conjugated fragment and introducing the isotope effect, the oscillator strength can be increased and high-frequency vibrations can be suppressed, thereby promoting the radiative transition rate of the molecule and suppressing the non-radiative transition rate. The nanoparticles prepared using the above-mentioned aggregation-induced luminescence material have the advantages of high brightness, large Stokes shift and good photostability, and have excellent effects in the surgical resection of in situ breast cancer and sentinel lymph nodes in mice guided by dual-modality imaging.

Description

Technical Field

[0001] The present invention relates to the technical field of aggregation-induced luminescence materials, and in particular to a class of near-infrared second-zone aggregation-induced luminescence materials, a preparation method thereof, and an application thereof in dual-modality imaging-guided surgical navigation. Background Art

[0002] High-efficiency near-infrared second-region luminescent materials are the key to achieving good fluorescence imaging effects. When constructing near-infrared second-region luminescent materials, a fast radiation transition rate (k r ) and the limited nonradiative transition rate (k nr ) plays an important role in improving luminous efficiency. However, due to the limitation of energy gap law, it is difficult to achieve fast k r and restricted k nr It is quite difficult.

[0003] To date, most NIR-II fluorophore design principles have been based on two main principles: 1) extending the π-conjugation length; and 2) enhancing intramolecular donor-acceptor (DA) interactions. However, due to the cumbersome synthesis steps, poor solubility, and structural instability caused by the extended π-conjugation, the first strategy has been difficult to achieve satisfactory results in practical applications. Furthermore, in the aggregated state, intermolecular π-π interactions can cause fluorescence quenching (ACQ), promoting nonradiative transitions and resulting in weak or no luminescence, limiting improvements in imaging quality.

[0004] Designing DA or D-π-A type structures with one or more donors or acceptors to narrow the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is another strategy for constructing NIR-II luminescent materials. The luminescence efficiency of a molecule is closely related to the overlap between the HOMO and LUMO. However, when too strong donors and acceptors are introduced, severe twisted intramolecular charge transfer (TICT) often leads to less overlap, resulting in low oscillator strength and reduced luminescence efficiency. In addition, in polar physiological environments, the TICT process will further promote non-radiative transitions. Therefore, when constructing DA or D-π-A type NIR-II luminescent materials, enhancing radiative transitions and limiting non-radiative transitions are of great significance for fluorescence imaging, but are also full of challenges.

[0005] When a molecule is excited, the energy of the excited state returns to the ground state primarily in the form of light and heat. The strength of the luminescence and photothermal effects determines the molecular applications in fluorescence imaging, photothermal therapy, and photoacoustic imaging. However, the lack of means to regulate radiative and nonradiative transitions has severely hampered the development of such functional materials. Fortunately, aggregation-induced emission (AIE) materials offer an effective strategy to address this issue. The intramolecular motion of AIE materials in dispersed or aggregated states provides a promising platform for modulating the strength of radiative and nonradiative transitions. Previous work has demonstrated that by introducing long alkyl chains as spacers to promote excited-state molecular motion, the energy of the excited state can be efficiently converted into heat in the aggregated state. Therefore, if the π-conjugated segments are rationally extended to enhance intermolecular interactions, excited-state molecular motion can be restricted, suppressing nonradiative transitions and promoting radiative ones. Furthermore, the extension of the π-conjugated segments can promote the delocalization of the HOMO orbital, thereby enhancing the oscillator strength of organic light-emitting molecules. Furthermore, replacing high-frequency carbon-hydrogen bonds with carbon-deuterium bonds can reduce nonradiative transitions caused by high-frequency vibrations. Therefore, it is expected that the expansion of π conjugation length and isotope effect will develop a novel nanostructured ... r It can also inhibit k nr NIR-II AIE molecules with high luminescence efficiency. Summary of the Invention

[0006] The present invention aims to provide a NIR-II luminescent material with AIE properties. By extending the length of the π-conjugated fragment and introducing the isotope effect, the oscillator strength is enhanced and high-frequency vibrations are suppressed, thereby promoting radiative transitions and suppressing non-radiative transitions of the molecule. The luminescent material of the present invention has the advantages of high brightness, large Stokes shift, and good photostability. It has excellent imaging capabilities in dual-modal imaging-guided in situ breast cancer and sentinel lymph node resection in mice.

[0007] Technical Solution: The target molecule of this invention uses thionaphthalenetetracarboxylic acid diimide, a strong electron-donating molecule, as an electron acceptor, and tetraphenylethylene as a molecular rotor and electron donor, to construct an organic fluorescent material with intramolecular charge transfer characteristics. By extending the π conjugation length and introducing the isotope effect, the intensity of the radiative oscillator is increased while suppressing high-frequency vibrations, thereby improving luminous efficiency.

[0008] Beneficial Effects: The invention provides a fluorescent material with high luminescence efficiency in the NIR II (900nm to 1500nm) region. By extending the length of the π-conjugated fragment and introducing the isotope effect, the oscillator strength can be enhanced and high-frequency vibrations can be suppressed, thereby promoting radiative transitions of molecules and suppressing non-radiative transitions. Nanoparticles prepared using this aggregation-induced emission material have the advantages of high brightness, large Stokes shift, and good photostability, enabling precise resection of in situ breast cancer and sentinel lymph nodes in mice. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 Shown are the synthetic routes of NDA-TPE, NDA-PTPE, and NDA-PDTPE. Figure 2 Shown are the AIE property tests of NDA-TPE, NDA-PTPE, and NDA-PDTPE.

[0010] Figure 3 Shown is the preparation process of NDA-PDTPE nanoparticles.

[0011] Figure 4 Shown is the particle size characterization of NDA-PDTPE nanoparticles.

[0012] Figure 5 Shown are the photophysical property characterizations of NDA-TPE, NDA-PTPE, and NDA-PDTPE nanoparticles.

[0013] Figure 6 Shown is the biocompatibility evaluation of NDA-PDTPE nanoparticles at the cellular and animal levels.

[0014] Figure 7 Shown is an image of a lymph node.

[0015] Figure 8 Shown is an in vivo angiogram.

[0016] Figure 9 Shown are photoacoustic and fluorescence imaging of orthotopic breast cancer in mice.

[0017] Figure 10 Precision excision of orthotopic mammary carcinoma and sentinel lymph nodes in the indicated mice. DETAILED DESCRIPTION

[0018] In order to have a clearer understanding of the technical features, objectives and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. However, the embodiments of the present invention are not limited thereto.

[0019] The reagents used in the following examples are all available from commercial sources.

[0020] Example 1: Synthesis of compound NDA-TPE

[0021]

[0022] Under a nitrogen atmosphere, p-bromophenylacetonitrile (1960 mg, 10 mmol) was dissolved in 10 mL of ultra-dry DMF. Sodium cyanide (800 mg, 20 mmol) was slowly added to the flask in an ice bath and stirred for 0.5 h. Carbon disulfide (760 mg, 10 mmol) was then slowly injected into the flask. The ice bath was removed, the temperature was raised to room temperature, and the mixture was stirred for 2 h. NDI (1143 mg, 1 mmol) was then added to the flask and allowed to react for 1 h. After the reaction, the reaction mixture was poured into 200 mL of saturated sodium chloride solution and filtered. The filter cake was dried and purified by column chromatography to obtain a dark blue solid, NDA-PBr (yield 60%). 1 H NMR (500 MHz, CDC l3 )δ[ppm]:7.67(d,J=8.0Hz,4H),7.56(d,J=7.9Hz,4H),4.22–4.08(m,4H),1.99(s,2H),1.27(t,J=35.6Hz,64H),0.85(d,J=5.6Hz,12H). 13 C NMR (126 MHz, CDC l3 )δ[ppm]:162.07,161.98,158.35,146.86,145.66,132.73,131.81,128.90,124.94,123.66,116.63,1 15.81,115.54,100.59,46.08,36.35,31.90,31.48,30.09,29.66,29.58,29.37,26.36,22.70,14.13.

[0023] Under a nitrogen atmosphere, NDA-PBr (150 mg, 0.11 mmol), 4,4,5,5-tetramethyl-2-(1,2,2-triphenylvinyl)-1,3,2-dioxaborolane (252 mg, 0.66 mmol), potassium carbonate (46 mg, 0.33 mmol), and tetrakis(triphenylphosphine)palladium (38 mg, 0.033 mmol) were dissolved in a mixed solution of tetrahydrofuran (15 mL) and deionized water (5 mL) and reacted at 100°C for 12 h. After the reaction, the reaction solution was cooled to room temperature and extracted three times with dichloromethane, and the organic phase was dried over sodium sulfate. The crude product obtained by vacuum distillation was purified by column chromatography to obtain a blue solid NDA-TPE (yield 43%). 1 H NMR (500 MHz, CDC l3 )δ[ppm]:7.44(d,J=8.4Hz,4H),

[0024] 7.21–7.00(m,34H),4.19(dt,J=11.7,5.8Hz,4H),2.04(s,2H),

[0025] 1.27(m,64H),0.84(dt,J=13.3,6.7Hz,12H). 13 C NMR (126 MHz, CDC l3 )δ[ppm]:162.07,162.04,162.00,161.98,158.35,146.86,

[0026] 146.75,145.78,145.66,132.73,131.83,131.81,128.89,124.94,

[0027] 123.66,116.63,115.81,115.78,115.55,115.54,100.59,46.08,31.94,

[0028] 31.90,30.09,29.70,29.66,29.63,29.37,29.35,22.70,14.13.MS

[0029] (MALDI-TOF)[m / z]:calcd for C112H120N4O4S4,1713.82260; found,1713.87008.

[0030] Example 2: Synthesis of compound NDA-PTPE

[0031]

[0032] Blue solid NDA-PTPE was synthesized based on NDA-TPE (yield 87%). 1 H NMR (500MHz, CDCl3) δ [ppm]: 7.70 (s, 8H), 7.41 (d, J = 7.8Hz, 4H), 7.09 (ddd, J = 10.1, 7.8,3.2Hz,34H),4.22–4.12(m,4H),2.02(s,2H),1.22(m,64H),0.87–0.80(m,12H). 13C NMR (126MHz, CDCl3) δ [ppm]: 162.19, 162.13, 157.16, 147.23, 147.11, 145.86, 145.71, 143. 68,143.63,141.51,141.45,140.33,137.30,132.04,131.64,131.43,131.35,127.84,127.7 7,127.67,127.62,126.58,126.18,125.09,116.99,115.73,115.51,101.40,46.06,36.32, 31.92,31.48,30.09,29.65,29.36,29.33,26.36,22.67,14.13.MS(MALDI-TOF)[m / z]:calcd forC 124 H 128 N4O4S4,1865.88520; found,1866.83361.

[0033] Example 3: Synthesis of compound NDA-PDTPE

[0034]

[0035] Under a nitrogen atmosphere, zinc powder (0.27 g, 12.6 mmol), deuterated dibenzophenone (762 mg, 3 mmol) and 4-bromobenzophenone (0.8 g, 4.2 mmol) were dissolved in ultra-dry tetrahydrofuran (60 mL). Titanium tetrachloride (1.38 mL, 12.6 mmol) was slowly added dropwise under ice bath conditions and reacted for 0.5 h. The reaction solution was then refluxed for 12 h. After completion of the reaction, the reaction was quenched with deionized water and extracted three times with dichloromethane, and the organic phase was dried over sodium sulfate. The crude product obtained by vacuum distillation was purified by column chromatography to obtain a white solid DTPE-Br (yield 38%). 1 H NMR (500MHz, CDCl3) δ [ppm]: 7.22 (d, J = 7.6 Hz, 2H), 7.10 (s, 3H), 7.01 (s, 2H), 6.89 (d, J = 7.6 Hz, 2H).

[0036] Under a nitrogen atmosphere, DTPE-Br (421 mg, 1 mmol), 1,1'-bis(diphenylphosphino)ferrocenepalladium dichloride (15 mg, 0.02 mmol), and potassium acetate (196 mg, 2 mmol) were dissolved in 1,4-dioxane (30 mL) and refluxed for 12 hours. After completion of the reaction, the reaction solution was cooled to room temperature and extracted three times with dichloromethane. The organic phase was then dried over sodium sulfate. The crude product obtained by vacuum distillation was purified by column chromatography to obtain DTPE-DB as a white solid (yield 88%). 1 H NMR (500MHz, CDCl3) δ [ppm]: 7.54 (d, J = 7.1Hz, 2H), 7.09 (s, 3H), 7.05–6.99 (m, 4H), 1.31 (s, 12H).

[0037] Blue solid NDA-PDTPE was synthesized based on NDA-TPE (yield 84%). 1 H NMR (500MHz, CDCl3) δ [ppm]: 7.72 (s, 6H), 7.42 (d, J = 7.8Hz, 4H), 7.17–7.04 (m, 16H), 4.19 (dd,J=22.1,15.7Hz,4H),2.03(s,2H),1.46–0.99(m,64H),0.83(tt,J=14.2,6.9Hz,12H). 13 C NMR(126MHz, CDCl3)δ[ppm]:161.06,161.00,156.01,146.13,146.00,144.74,144.60,142.59,1 42.51,142.40,142.35,140.35,139.19,136.21,130.94,130.33,130.25,126.74,126.67,126.57 ,126.52,125.47,125.07,123.98,115.86,114.64,114.39,44.97,35.22,30.81,30.78,30.41,28 .99,28.57,28.54,28.51,28.46,28.25,28.22,25.27,21.56,13.01.MS(MALDI-TOF)[m / z]:calcd for C 124 H 108 D 20 N4O4S4,1886.01073; found,1886.01480.

[0038] Example 4: Characterization of AIE properties of NDA-TPE, NDA-PTPE and NDA-PDTPE

[0039] Figure 2 The fluorescence spectra of the materials obtained in Examples 1-3 under different water content conditions are shown in the figure. As can be seen from the figure, NDA-TPE, NDA-PTPE and NDA-PDTPE emit weak light in the good solvent N,N-dimethylformamide. With the addition of poor solvent water, the fluorescence begins to gradually increase. This shows that these materials all have AIE properties. At the same time, the α AIE (The ratio of fluorescence intensity when the ratio of poor solvent water is 95% and 0%) is 8.2 and 6.7 respectively, which is better than NDA-TPE (α AIE is 2.3), which shows that NDA-PDTPE has better aggregation-induced emission properties.

[0040] Example 5: Preparation of nanoparticles using NDA-TPE, NDA-PTPE and NDA-PDTPE

[0041] Weigh 1 mg of NDA-TPE and 5 mg of Pluronic F127 and dissolve them in 1 mL of tetrahydrofuran solution, then sonicate for 3 minutes. Add 5 mL of deionized water to a centrifuge tube and set the stirring speed to 900 rpm. Slowly add the tetrahydrofuran solution dropwise to the water, stir overnight, remove the solvent tetrahydrofuran, and filter with a 0.22 μm pore size filter membrane to obtain nanoparticles ( Figure 3 ).

[0042] Example 6: Particle Size Characterization of NDA-PDTPE Nanoparticles

[0043] Figure 4 Figure 3 shows the dynamic light scattering (DLS) particle size distribution and transmission electron microscopy (TEM) morphology of NDA-PDTPE nanoparticles. DLS shows that the particle size of NDA-PDTPE nanoparticles is approximately 156 nm, and the polydispersity index (PDI) is 0.056, indicating that the prepared nanoparticles have good uniformity.

[0044] Example 7: Characterization of Photophysical Properties of NDA-TPE, NDA-PTPE, and NDA-PDTPE Nanoparticles

[0045] Figure 5The absorption and emission spectra of the nanoparticles are shown in Figure 2. The absorption and emission peaks of NDA-PDTPE nanoparticles are located at 673 nm and 1018 nm, respectively, resulting in a Stokes shift of 345 nm. A large Stokes shift helps reduce the overlap of the absorption and emission spectra and suppresses self-absorption. The fluorescence quantum yields of NDA-TPE, NDA-PTPE, and NDA-PDTPE nanoparticles are 1.23%, 2.33%, and 2.61%, respectively, indicating that NDA-PDTPE nanoparticles possess superior luminescence properties, which facilitates improved imaging results.

[0046] Example 8: Biocompatibility evaluation of NDA-PDTPE nanoparticles at the cellular and animal levels

[0047] The cytotoxicity of NDA-PDTPE nanoparticles was evaluated using 4T1 cells. 4T1 cells were plated in 96-well plates and cultured for 24 hours, then co-cultured with different concentrations of NDA-PDTPE nanoparticles for 24 hours. MTT was used to detect cell toxicity. The test results are shown in Figure 6 a, NDA-PDTPE nanoparticles have no obvious cytotoxicity.

[0048] Healthy BALB / c nude mice were used to evaluate the toxicity of NDA-PDTPE nanoparticles at the animal level. 100 μL of NDA-PDTPE nanoparticles were injected into the tail vein of Balb / c nude mice. One week later, the main organs (heart, liver, spleen, lung, and kidney) of the nude mice were harvested for pathological analysis. Figure 6 As shown in b, the results showed that there were no obvious lesions in the main organs of the mice, indicating that NDA-PDTPE nanoparticles have excellent biocompatibility.

[0049] Example 9: Lymph Node Imaging

[0050] Under anesthesia, 100 μL of NDA-PDTPE nanoparticles were injected into healthy mice through the paw pad and imaged using a small animal imager. Different filters (long pass 880 nm, long pass 1000 nm, and long pass 1300 nm) were used to collect the fluorescence signals of the mouse lymph nodes. Figure 7 As shown, the fluorescence imaging background is the weakest and the contrast is the best when using a long-pass 1300nm filter.

[0051] Example 10: In vivo angiography

[0052] Under anesthesia, 100 μL of NDA-PDTPE nanoparticles were injected into healthy mice through the tail vein, and the fluorescence signal of the mouse blood vessels was collected using a fluorescence imager (long pass 1300 nm). Figure 8As shown, after injection of nanoparticles, blood vessels throughout the mouse body were clearly visible, and the signal-to-noise ratio (SBR) could reach 2.7.

[0053] Example 11: Photoacoustic and fluorescence imaging of in situ breast cancer in mice

[0054] 100 μL of NDA-PDTPE nanoparticles were injected into mice with orthotopic breast cancer via the tail vein, and fluorescence imaging and photoacoustic imaging images of the tumor site were collected at 0, 2, 8, 12, and 24 h after injection. Figure 9 The fluorescence imaging and photoacoustic imaging results show that the photoacoustic and fluorescence signal intensities at the tumor site gradually increased over time, reaching a peak at 12 hours, indicating that 12 hours after injection is the optimal time for surgical resection.

[0055] Example 12: Fluorescence-guided precise resection of in situ breast cancer and sentinel lymph nodes in mice

[0056] Figure 10 To successfully remove orthotopic breast cancer and sentinel lymph nodes in mice under the guidance of photoacoustic and fluorescence dual-modality imaging.

Claims

1. A near-infrared second-region aggregation-induced emission material, characterized in that: The structure of the near-infrared second-region aggregation-induced emission material is selected from one of the following structures: 、 、 。 2. A method for preparing the near-infrared second-region aggregation-induced emission material according to claim 1, characterized in that: The synthesis route of the near-infrared second-region aggregation-induced emission material is as follows: 。 3. A composition, characterized in that The composition comprises the near-infrared second-region aggregation-induced emission material according to claim 1 and a matrix for encapsulating the near-infrared second-region aggregation-induced emission material.

4. The composition according to claim 3, wherein The composition is in the form of nanoparticles.

5. The composition according to claim 4, wherein The composition emits fluorescence in the near-infrared region of 900 nm to 1500 nm.

6. Use of the composition according to any one of claims 3 to 5 in the preparation of a fluorescent contrast agent. 7 . Use of the composition according to claim 3 in the preparation of a fluorescent contrast agent for use in dual-modality imaging-guided surgical navigation.

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