阅读说明：本技术 基于异佛尔酮-肉桂醛的粘度荧光探针的制备和应用 (Preparation and application of viscosity fluorescent probe based on isophorone-cinnamaldehyde ) 是由 李春艳 廖沁婷 徐芬 于 2021-07-20 设计创作，主要内容包括：本发明涉及了基于异佛尔酮-肉桂醛的粘度荧光探针的制备和应用,该荧光探针的结构式为：本发明提供了以异佛尔酮、丙二腈、4-(二甲氨基)肉桂醛等为原料合成该荧光探针的制备方法；该荧光探针是一种近红外粘度荧光探针；首先,该荧光探针对粘度表现出很高的灵敏度,粘度增加,荧光强度显著增强；其次,该荧光探针对粘度表现出很高的选择性,不受其他活性氧、活性氮、活性硫以及生物硫醇的干扰；并且,该荧光探针具有较好的光稳定性,在120min持续光照下,荧光强度不变；此外,该荧光探针应用于活细胞内粘度的检测。(The invention relates to preparation and application of a viscosity fluorescent probe based on isophorone-cinnamaldehyde, wherein the structural formula of the fluorescent probe is as follows: the invention provides a preparation method for synthesizing the fluorescent probe by taking isophorone, malononitrile, 4- (dimethylamino) cinnamaldehyde and the like as raw materials; the fluorescent probe is a near-infrared viscosity fluorescent probe; firstly, the fluorescent probe shows high sensitivity to viscosity, the viscosity is increased, and the fluorescence intensity is obviously enhanced; secondly, the fluorescent probe shows high selectivity to viscosity and is free from other active oxygen and active nitrogenActive sulfur and biological thiol interference; in addition, the fluorescent probe has better light stability, and the fluorescence intensity is unchanged under the continuous illumination for 120 min; in addition, the fluorescent probe is applied to the detection of the viscosity in living cells.)

1. A viscosity fluorescent probe based on isophorone-cinnamaldehyde has the following structure:

2. the method for preparing the isophorone-cinnamaldehyde-based viscosity fluorescent probe according to claim 1, which comprises the following steps:

1) adding 15-20 mL of absolute ethyl alcohol into a 50mL round-bottom flask, adding 1 equivalent of isophorone and 1-1.5 equivalents of malononitrile into the flask, mixing, dropwise adding piperidine, and adding N₂Under the protection condition, stirring and refluxing the reaction mixture at 50-80 ℃ for 10-14 h, stopping the reaction, cooling to room temperature, pouring into a beaker filled with 70-100 g of ice water, separating out a brown yellow solid, standing for 1-2 h, performing suction filtration, drying, collecting a crude product, recrystallizing with n-heptane, performing suction filtration, and drying to obtain a yellow brown solid compound, namely malononitrile-isophorone;

2) adding 15-25 mL of absolute ethyl alcohol into a 50mL round-bottom flask, mixing 1 equivalent of malononitrile-isophorone with 1-5 equivalents of 4- (dimethylamino) cinnamaldehyde, stirring and refluxing a reaction mixture for 8-15 h at 70-90 ℃, stopping the reaction, removing a solvent by reduced pressure distillation to obtain a crude product, performing column chromatography by using petroleum ether/dichloromethane with a volume ratio of 1: 2-3: 1, and removing the solvent to obtain a reddish brown solid, namely the fluorescent probe.

3. The use of the isophorone-cinnamaldehyde-based viscosity fluorescent probe according to claim 1, wherein the fluorescent probe is used for the detection of viscosity in living cells.

Technical Field

The invention belongs to the technical field of fluorescent probes, and particularly relates to preparation and application of a viscosity fluorescent probe based on isophorone-cinnamaldehyde.

Background

Viscosity is an important microenvironment parameter in biological systems and plays an important role in signal transmission, electron transmission, and inter-biomolecule interactions (r. kotani, h. sotome, h. okajima, s. yokoyama, y. nakaike, a. kashiwagi, j. mater. chem. c,2017,5, 5248-. Intracellular viscosity abnormalities can disrupt cell function, leading to the development of a variety of diseases. Studies have shown that viscosity changes are closely related to various diseases such as hypertension, atherosclerosis, Alzheimer's disease, Diabetes, etc. (M.Kuimova, S.Botchway, A.Parker, M.Balaz, H.Colins, H.Anderson, Nature Chem,2009,1, 69-73; G.S.Zubenko, U.Kopp, T.Seto, L.L.Firestone, Psychopharmacology,1999,145, 175-. In view of the important physiological and clinical significance of viscosity, it is necessary to accurately detect viscosity changes.

In recent years, various viscometers for measuring large-volume liquids have been well developed, such as a ball drop viscometer, a piston viscometer, and a rotary viscometer. However, these measurements do not detect intracellular viscosity changes (K.Zhou, M.ren, B.Deng, W.Lin, New J.chem,2017,41, 11207-11511). The fluorescence imaging technology has the advantages of high sensitivity, high specificity, small damage to cells, simple operation and the like, and becomes one of the strongest tools for detecting target substances in vivo in real time. So far, some fluorescent probes for imaging intracellular viscosity have been reported (J.yin, P.Min, W Lin, anal.chem.,2019,91, 8415-. However, most fluorescent materials still have the limitations of short emission wavelength, high background fluorescence, and the like. Therefore, it is very urgent and meaningful to design and synthesize a fluorescent probe having a long wavelength and a high response time.

Disclosure of Invention

In accordance with the proposed requirements, the present inventors have conducted intensive studies to provide a near infrared viscofluorescence probe based on isophorone-cinnamaldehyde after a great deal of creative work.

The technical scheme of the invention is that the viscosity fluorescent probe based on isophorone-cinnamaldehyde has the following structural formula:

a preparation method of a viscosity fluorescent probe based on isophorone-cinnamaldehyde. The method comprises the following steps:

1) adding 15-20 mL of absolute ethyl alcohol into a 50mL round-bottom flask, adding 1 equivalent of isophorone and 1-1.5 equivalents of malononitrile into the flask, mixing, dropwise adding piperidine, and adding N₂Under the protection condition, stirring and refluxing the reaction mixture at 50-80 ℃ for 10-14 h, stopping the reaction, cooling to room temperature, pouring the mixture into a beaker filled with 70-100 g of ice water, separating out a brown yellow solid, standing for 1-2 h, performing suction filtration, drying, collecting a crude product, recrystallizing with n-heptane, performing suction filtration, and drying to obtain a yellow brown solid compound, namely malononitrile-isophorone (yield 60%). 2) Adding 15-25 mL of absolute ethyl alcohol into a 50mL round-bottom flask, mixing 1 equivalent of the product with 1-5 equivalents of 4- (dimethylamino) cinnamaldehyde, stirring and refluxing a reaction mixture for 8-15 h at 70-90 ℃, stopping the reaction, removing the solvent by reduced pressure distillation to obtain a crude product, performing column chromatography by using petroleum ether/dichloromethane in a volume ratio of 1: 2-3: 1, and removing the solvent to obtain a reddish brown solid, namely the fluorescent probe IC-V.

The invention has the beneficial effects that the viscosity fluorescent probe based on isophorone-cinnamaldehyde has good spectral response performance. First, the fluorescence spectrum properties of the probe were investigated. The fluorescent probe has no obvious near infrared emission peak at 700nm when being mixed with water; after mixing the probe with glycerol, a distinct near-infrared emission peak at 700nm appeared. And as the volume of the glycerol is increased, the viscosity is increased, and the near infrared fluorescence intensity of the probe is continuously enhanced. The linear detection range of the probe is from 1.29cp to 545.03cp, which shows that the probe can detect viscosity change with high sensitivity. Next, the ultraviolet absorption spectrum of the probe was investigated. The probe itself has an absorption band at 500 nm; after mixing with glycerol, the absorption peak at 500nm is red-shifted and gradually increased, and the solution color changes from pinkIt is purple. Then, the selectivity of the probe was investigated. The probe and active oxygen (H) were examined₂O₂,ClO^-) Active Nitrogen (NO)₂ ^-,NO₃ ^-) Active sulfur (HS)^-,SO₃ ^2-,S₂O₄ ^2-,SO₄ ^2-) Common cation (K)⁺,Mg²⁺,Na⁺,Fe²⁺,Zn²⁺,Ag⁺,Cu²⁺,NH₄ ⁺) Common anion (Cl)^-,Br^-,I^-,CH₃COO^- _,CO₃ ^2-) (200. mu.M) and the fluorescence response of biological thiols (GSH). As a result, it was found that only glycerol having a large viscosity causes a change in the fluorescence spectrum, and that other analytes have no significant influence on the fluorescence spectrum of the probe. Finally, the effect of pH on the viscosity of the fluorescent probes was investigated, and the viscosity measurement by the fluorescent probes was not affected when the pH was between 5.0 and 8.0. In addition, the fluorescent probe has good light stability, and the fluorescence intensity is kept stable within 120 min.

An application of a viscosity fluorescent probe based on isophorone-cinnamaldehyde. Only the fluorescent probe was added to the cells and the red channel had little fluorescence. The cells are treated with Nystatin (Nystatin) to stimulate the viscosity to rise in the cells, and then a probe is added to detect that a strong red fluorescent signal appears in the cells. These results indicate that the fluorescent probe can monitor changes in intracellular viscosity, which provides a reliable means for monitoring in vivo and viscosity-related pathologies in humans.

Drawings

FIG. 1 shows a synthetic route of a fluorescent probe.

FIG. 2 is a graph showing fluorescence spectra of fluorescent probes in solutions of different viscosities.

The abscissa is wavelength and the ordinate is fluorescence intensity. The concentration of the fluorescent probe was 10. mu.M, and the concentration of glycerol (Gly) was: 0, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99%, and viscosity values of 1.05,1.29,1.71,2.37,3.44,5.56,9.02,17.43,40.13,121.91,545.03cp, respectively. The fluorescence excitation wavelength was 530 nm.

FIG. 3 is a graph of the fluorescent linear response of fluorescent probes to different viscosities.

FIG. 4 is a graph of UV-VIS absorption spectra of fluorescent probes in solutions of different viscosities.

FIG. 5 is a graph showing selectivity of fluorescent probes for viscosity measurement.

The concentration of the fluorescent probe was 10. mu.M, the concentration of glycerol was 99%, and the concentration of the other analytes was 200. mu.M.

FIG. 6 is a graph showing the effect of pH on fluorescent probes.

FIG. 7 is a graph showing the time-dependent change in fluorescence intensity of a fluorescent probe when the probe is continuously irradiated with laser light.

FIG. 8 is a cytotoxicity assay. The abscissa is the concentration of the fluorescent probe and the ordinate is the survival rate of the cells.

FIG. 9 is an image of a cell showing the effect of fluorescent probe on viscosity. The first row of cells was stained with the probe for 20 min. The second row of cells were treated with Nystatin for 30min and then stained with the probe for 20 min.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but is not limited thereto.

Example 1:

synthesis of fluorescent probes

The synthetic route is shown in figure 1. Synthesis of malononitrile-isophorone: 15mL of absolute ethanol was added to a 50mL round-bottom flask, isophorone (0.95g,6.9mmol) and malononitrile (0.45g,6.9mmol) were added to the round-bottom flask and mixed, 10. mu.L of piperidine was added, and the mixture was stirred and refluxed at 60 ℃ for 12 hours, and reacted with N₂And (4) protecting. After the reaction was completed, the reaction mixture was cooled to room temperature, and then poured into a beaker containing 80g of ice water to precipitate a tan solid, which was left to stand for 1 hour, followed by suction filtration and drying to obtain a crude product, which was then recrystallized from n-heptane, and suction filtration and drying to obtain 0.77g of a yellowish brown compound (yield 60%).

Synthesis of fluorescent Probe (IC-V): in a 50mL round-bottom flask, 15mL of absolute ethanol was added, Compound 1(27.9mg,0.15mmol) and 4- (dimethylamino) cinnamaldehyde (26.2mg,0.15mmol) were added to the flask and mixed, and finally 0.1mL of piperidine and 0.1mL of acetic acid were added dropwise, and the reaction mixture was stirred at 8 deg.CStirring and refluxing for 12h at 0 ℃, stopping the reaction, distilling to remove the solvent to obtain a crude product, performing column chromatography by using petroleum ether/dichloromethane (1:1) as an eluent, decompressing, distilling to remove the solvent to obtain 31.3mg of a reddish brown solid product (yield 60%), namely the fluorescent probe.¹H NMR(400MHz,CDCl₃,ppm):δ7.41(d,J＝8.0Hz,2H),7.02(d,J＝8.0Hz,1H),6.80-6.75(m,3H),6.45(s,2H),6.24(s,1H),3.02(s,6H),2.01(s,4H),1.05(s,6H).¹³C NMR(100MHz,CDCl₃,ppm):δ149.9,140.7,138.8,138.4,129.9,129.4,128.4,127.7,126.8,123.4,123.0,111.4,111.1,76.3,76.6,43.3,39.2,38.3,30.4,28.7.MS(TOF):344.2.

Example 2:

fluorescent probe and preparation of different viscosity solutions

Preparation of probe solution: weighing a certain amount of probe, dissolving in dimethyl sulfoxide to prepare 1 × 10^-4M probe solution. Preparing solutions with different viscosities: adding 1mL of probe solution into a 10mL volumetric flask, adding glycerol (Gly) with different percentages, and performing constant volume with buffer solution to obtain the concentration of 1.0 × 10-⁵mol·L^-1The fluorescent probe and glycerol with different viscosities are mixed with the solution to be detected.

Example 3:

measurement of fluorescence spectra of the action of fluorescent probes on solutions of different viscosities

FIG. 2 shows fluorescence spectra of the effect of fluorescent probe on different viscosity solutions, the concentration of the fluorescent probe is 10 μ M, and the concentration of glycerol (Gly) is respectively: 0, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99%, corresponding to a viscosity of 1.05,1.29,1.71,2.37,3.44,5.56,9.02,17.43,40.13,121.91,545.03 cp. The excitation wavelength is fixed to 530nm, and the emission wavelength range is 550-900 nm. The slit width was 5.0nm/5.0nm, and the fluorescence measuring instrument used was a Hitachi F4600 fluorescence spectrophotometer. As can be seen from FIG. 2, the fluorescent probe itself has no significant near-infrared emission peak at near-infrared (700 nm); after addition of the glycerol solution, a distinct near-infrared emission peak at 700nm appeared. This is because the probe follows the TICT mechanism, free-spinning in a non-viscous or low viscosity solution, and the excited dye returns to the ground state through a nonradiative transition process. With the increase of the concentration of the glycerol, the viscosity of the solution increases, the viscous environment can inhibit the rotation of molecules, excited state molecules are prevented from being transited to a ground state through non-radiation, and the excited state molecules can be returned to the ground state only through radiation transition, so that the fluorescence intensity of near-infrared molecules of the probe is continuously enhanced. FIG. 3 is a graph of the linear response of the probe to viscosity. The logarithm of the fluorescence intensity and the logarithm of the viscosity have a linear relation, and the linear range is 1.29-545.03 cp, which shows that the probe can detect the viscosity with high sensitivity.

Example 4:

measurement of ultraviolet-visible absorption spectrum of fluorescent probe and viscosity effect

FIG. 4 is the UV-VIS absorption spectrum of the fluorescent probe after the action of viscosity, the concentration of the fluorescent probe is 10 μ M, and the concentration of glycerol (Gly) is 0% and 99%. The instrument for measuring the ultraviolet visible absorption spectrum is an Agilent Cary60 ultraviolet visible spectrophotometer. As can be seen from FIG. 4, the probe itself has an absorption band at 510 nm; after addition of the glycerol solution, the absorption peak red-shifted with increasing viscosity and the absorption peak intensity increased.

Example 5:

selectivity of fluorescent probes for viscosity measurements

FIG. 5 is a graph showing selectivity of fluorescent probes for viscosity measurement. Examination was conducted by adding a buffer solution, glycerol (Gly, 99%), and active oxygen (H) to a 10. mu.M fluorescent probe solution₂O₂,ClO^-) Active Nitrogen (NO)₂ ^-,NO₃ ^-) Active sulfur (HS)^-,SO₃ ^2-,S₂O₄ ^2-,SO₄ ^2-) Common cation (K)⁺,Mg²⁺,Na⁺,Fe²⁺,Zn²⁺,Ag⁺,Cu²⁺,NH₄ ⁺) Common anion (Cl)^-,Br^-,I^-,CH₃COO^-,CO₃ ^2-) And the fluorescence response of biological thiols (GSH) (200 μ M). As can be seen from FIG. 5, only the viscosity causes a change in the fluorescence spectrum, and the other analytes have no significant effect on the fluorescence spectrum of the probe. These results indicate that the fluorescent probe has a good selectivity for viscosity.

Example 6:

effect of solution pH on fluorescence Properties of fluorescent probes for determining viscosity

The effect of pH on the fluorescence spectrum of the fluorescence probe for viscosity measurement was examined, and the results are shown in FIG. 6. The pH range studied by us is 3.0-10.0, and the concentration of the fluorescent probe is 10 mu M. As can be seen from the figure, the fluorescence intensity of the fluorescent probe is basically unchanged along with the change of pH, which shows that the pH has no great influence on the probe. However, after the glycerol solution is added, the fluorescence intensity ratio is obviously enhanced in the pH range of 5.0-8.0. In summary, when the pH value is between 5.0 and 8.0, the pH value range which does not affect the measurement of the viscosity by the fluorescent probe is a more suitable pH value range, which is very beneficial for the probe to be used for measuring the viscosity in an actual sample.

Example 7:

photostability determination of fluorescent probes and viscosity effects

We investigated the photostability assay of the effect of fluorescent probes on viscosity, the results of which are shown in FIG. 7. As can be seen from the figure, the probe has rapid response to viscosity, and the fluorescence intensity does not change under the continuous illumination for the next 120min, which shows that the fluorescent probe has good light stability and can meet the requirement of real-time monitoring in actual samples.

Example 8:

application of fluorescent probe in living cell

First, we performed cytotoxicity assays as shown in fig. 8. When 0-30 mu M of IC-V probe is added, the survival rate of the cells is over 90 percent. This can indicate that the fluorescent probe is less toxic and can be used to detect viscosity in living cells. Then, we investigated the application of fluorescent probes in living cells, and selected HeLa cells for confocal microscopy, and the results are shown in fig. 9. Only the fluorescent probe was added to the cells in the first row and the red channel had little fluorescence. Nystatin (Nystatin) is reported in the literature to stimulate intracellular viscosity abnormalities. The cells in the second row are pretreated with Nystatin for 30min to stimulate the production of intracellular viscosity, and then stained with a probe for 20min to detect the presence of strong red fluorescence signals in the cells. These results indicate that the fluorescent probe can monitor the change of intracellular viscosity content, which provides a reliable means for monitoring the pathological changes in the human body and related to viscosity abnormality.