Near-infrared two-region aggregation-induced emission material as well as preparation method and application thereof

Abstract

The invention discloses a high-efficiency near-infrared two-region aggregation-induced emission material, a preparation method thereof and application of the high-efficiency near-infrared two-region aggregation-induced emission material in bimodal surgical navigation. According to the molecular structure, the organic near-infrared two-region material with an intramolecular charge transfer characteristic is constructed by taking thionaphthalene tetracarboxylic acid diimide as an electron acceptor group and tetraphenylethylene as a molecular rotor and an electron donor unit. By expanding the length of a pi conjugate fragment and introducing an isotope effect, the oscillator strength can be improved, and high-frequency vibration can be inhibited, so that the radiative transition rate of molecules is promoted, and the non-radiative transition rate is inhibited. The nanoparticles prepared from the aggregation-induced emission material have the advantages of high brightness, large Stokes shift and good light stability, and have an excellent effect in bimodal imaging guided mouse in-situ breast cancer and sentinel lymph node operation excision.

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 surgical navigation guided by dual-modality imaging. Background Art

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

[0003] So far, most NIR-II fluorophores are designed based on the following two principles: 1) extending the π conjugation length; 2) enhancing the intramolecular donor-acceptor (DA) interaction. However, due to the cumbersome synthesis steps, poor solubility, and structural instability caused by π conjugation extension, the first strategy is difficult to achieve satisfactory results in practical applications. Moreover, in the aggregated state, the intermolecular π-π interaction will also cause fluorescence quenching (ACQ) problems, promote non-radiative transitions, and cause the molecules to emit weak or no light, limiting the improvement of imaging effects.

[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 further promotes 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 they are also challenging.

[0005] When a molecule is excited, the energy of the excited state returns to the ground state mainly in the form of light and heat. The strength of luminescence and photothermal effects determines the application direction of the molecule in the fields of fluorescence imaging, photothermal therapy and photoacoustic imaging. However, the lack of means to regulate radiative and non-radiative transitions has seriously hindered the development of such functional materials. Fortunately, aggregation-induced emission (AIE) materials provide an effective strategy to solve the above problems. The intramolecular motion of AIE materials in dispersed or aggregated states can provide a good platform for regulating the strength of radiative and non-radiative transitions. Previous work has shown that by introducing long alkyl chains as spacer units to promote the molecular motion of the excited state, the energy of the excited state can be effectively converted into heat in the aggregated state. Therefore, if the π-conjugated fragment is reasonably extended to enhance the interaction between molecules, the excited state molecular motion can be restricted, non-radiative transitions can be suppressed and radiative transitions can be promoted. On the other hand, the extension of the π-conjugated fragment can promote the delocalization of the HOMO orbital, thereby enhancing the oscillator strength of the organic light-emitting molecule. In addition, replacing high-frequency carbon-hydrogen bonds with carbon-deuterium bonds can reduce non-radiative 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, and by extending the length of the π-conjugated fragment and introducing the isotope effect, the oscillator strength is increased and high-frequency vibration is suppressed, thereby promoting the radiative transition of the molecule and suppressing the non-radiative transition. The luminescent material of the present invention has the advantages of high brightness, large Stokes shift and good photostability, and has excellent imaging capabilities in the removal of in situ breast cancer and sentinel lymph nodes in mice guided by dual-modal imaging.

[0007] Technical solution: The target molecule of the present invention selects thionaphthalene tetracarboxylic acid diimide with strong electron-donating properties 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 radiation oscillator intensity is increased while suppressing high-frequency vibration, thereby improving the luminous efficiency.

[0008] Beneficial effects: The invention provides a fluorescent material that can have 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 increased and high-frequency vibrations can be suppressed, thereby promoting the radiative transition of molecules and suppressing non-radiative transitions. The nanoparticles prepared using the above-mentioned aggregation-induced luminescence material have the advantages of high brightness, large Stokes shift and good photostability, and can achieve 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] Fig. 9 Shown are photoacoustic and fluorescence imaging of orthotopic breast cancer in mice.

[0017] Fig.10 Precision excision of orthotopic breast cancer and sentinel lymph nodes in the indicated mice. DETAILED DESCRIPTION

[0018] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation of the present invention is now described in detail with reference to the accompanying drawings. However, the implementation of the present invention is 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 nitrogen atmosphere, p-bromophenylacetonitrile (1960 mg, 10 mmol) was dissolved in 10 mL of ultra-dry DMF. Under ice bath conditions, sodium cyanide (800 mg, 20 mmol) was slowly added to the bottle and stirred for 0.5 h, then carbon disulfide (760 mg, 10 mmol) was slowly injected into the bottle, the ice bath was removed and then the temperature was raised to room temperature and stirred for 2 h. Then NDI (1143 mg, 1 mmol) was added to the flask and reacted for 1 h. After the reaction was completed, the reaction solution was poured into 200 mL of saturated sodium chloride solution and filtered, the filter cake was dried and purified by column chromatography to obtain dark blue solid NDA-PBr (yield 60%). 1 H NMR (500MHz, 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 (126MHz, 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 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), 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 then the organic phase was dried with 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 (500MHz, CDC l3)δ[ppm]:7.44(d,J=8.4Hz,4H),7.21–7.00(m,34H),4.19(dt,J=11.7,5.8Hz,4H),2.04(s,2H),1.27(m,64H),0.84(dt,J=13.3,6.7Hz,12H). 13 C NMR (126MHz, CDC l3 )δ[ppm]:162.07,162.04,162.00,161.98,158.35,146.86,146.75,145. 78,145.66,132.73,131.83,131.81,128.89,124.94,123.66,116.63,11 5.81,115.78,115.55,115.54,100.59,46.08,31.94,31.90,30.09,29.7 0,29.66,29.63,29.37,29.35,22.70,14.13.MS(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 (500 MHz, CDCl 3 )δ[ppm]:7.70(s,8H),7.41(d,J=7.8Hz,4H),7.09(ddd,J=10.1,7.8,3.2H z,34H),4.22–4.12(m,4H),2.02(s,2H),1.22(m,64H),0.87–0.80(m,12H). 13 C NMR (126 MHz, CDCl 3)δ[ppm]:162.19,162.13,157.16,147.23,147.11,145.86,145.71,143.68,143.63,14 1.51,141.45,140.33,137.30,132.04,131.64,131.43,131.35,127.84,127.77,127.67 ,127.62,126.58,126.18,125.09,116.99,115.73,115.51,101.40,46.06,36.32,31.9 2,31.48,30.09,29.65,29.36,29.33,26.36,22.67,14.13.MS(MALDI-TOF)[m / z]:calcd forC 124 H 128 N 4 O 4 S 4 ,1865.88520; found,1866.83361.

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

[0034]

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

[0036] Under 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 h. After the reaction, the reaction solution was cooled to room temperature and extracted three times with dichloromethane, and then the organic phase was dried with sodium sulfate. The crude product obtained by vacuum distillation was purified by column chromatography to obtain white solid DTPE-DB (yield 88%). 1 H NMR (500 MHz, CDCl 3 )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 (500 MHz, CDCl 3 )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 (126 MHz, CDCl 3 )δ[ppm]:161.06,161.00,156.01,146.13,146.00,144.74,144.60,142.59,142.51,142.40 ,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 N 4 O 4 S 4,1886.01073; 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, and the fluorescence gradually increases with the addition of the poor solvent water. 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 added is 95% and 0%) is 8.2 and 6.7 respectively, which is better than NDA-TPE (α AIE is 2.3), which indicates 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 min. Take 5 mL of deionized water and add it to a centrifuge tube, 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 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 about 156nm, 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 5are the absorption and emission spectra of the nanoparticles. The absorption and emission peaks of NDA-PDTPE nanoparticles are at 673nm and 1018nm, respectively, so its Stokes shift is 345nm. A large Stokes shift is beneficial to reducing the overlap of the absorption and emission spectra and inhibiting the self-absorption effect. 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 have better luminescence properties, which is beneficial to obtaining better imaging effects.

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

[0047] 4T1 cells were used to evaluate the cytotoxicity of NDA-PDTPE nanoparticles. 4T1 cells were plated in 96-well plates and cultured for 24 hours, then co-cultured with NDA-PDTPE nanoparticles of different concentrations for 24 hours, and the cytotoxicity was detected by MTT. 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 Balb / c nude mice via the tail vein, and the main organs (heart, liver, spleen, lung, and kidney) of the nude mice were taken for pathological analysis one week later. 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 signals of the mouse blood vessels were 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. Fig. 9 The fluorescence imaging and photoacoustic imaging effects. As can be seen from the figure, the photoacoustic and fluorescence signal intensity of the tumor site gradually increased with time and reached the highest at 12h, indicating that 12h after injection is the best time for surgical resection.

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

[0056] Fig.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. The near-infrared second-region aggregation-induced emission material according to claim 1, characterized in that: The near-infrared second-region aggregation-induced emission material has AIE properties.

3. A method for preparing the near-infrared second-region aggregation-induced emission material according to claim 1 or 2, characterized in that: The synthesis route of the near-infrared second-region aggregation-induced luminescence material is as follows:

4. A composition, characterized in that The composition comprises the near-infrared second-region aggregation-induced emission material according to claim 1 or 2 and a matrix for encapsulating the near-infrared second-region aggregation-induced emission material.

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

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

7. Use of the composition according to any one of claims 4 to 6 in the preparation of a fluorescent contrast agent.

8. Use of the composition according to any one of claims 4 to 6 in dual-modality imaging-guided surgical navigation.

Images