阅读说明：本技术 一种自报告光敏剂及其制备方法和应用 (Self-reporting photosensitizer and preparation method and application thereof ) 是由 严秀平 王东辉 于 2021-10-12 设计创作，主要内容包括：本发明公开了一种自报告光敏剂及其制备方法和应用,属于生物医学工程技术领域。本发明光敏剂在结构上包含一个扭曲的三苯胺(TPA)单元、三个苯环单元和三个氰乙烯基吡啶盐(PyA+)单元；制备方法简单,在水溶液中具有高单线态氧量子产率(124％),抗癌性能显著。同时,本发明光敏剂能够实现双色荧光的活细胞染色,并且发射颜色、强度和细胞内定位能在连续光照射下随着细胞死亡的程度同时变化,使TPA-3PyA+能够在原位实时监测光动力治疗过程。此外,在光动力治疗后,TPA-3PyA+仅能以绿色荧光点亮死细胞的细胞核,通过观察TPA-3PyA+的发光颜色变化可明显地区分活细胞和死细胞。(The invention discloses a self-reporting photosensitizer and a preparation method and application thereof, belonging to the technical field of biomedical engineering. The photosensitizer structurally comprises a twisted Triphenylamine (TPA) unit, three benzene ring units and three cyanovinylpyridine salt (PyA +) units; the preparation method is simple, the yield of singlet oxygen quanta in aqueous solution is high (124 percent), and the anticancer performance is obvious. Meanwhile, the photosensitizer can realize the living cell staining of double-color fluorescence, and the emission color, the emission intensity and the intracellular positioning can be simultaneously changed along with the death degree of cells under continuous light irradiation, so that the TPA-3PyA + can monitor the photodynamic therapy process in situ in real time. In addition, TPA-3PyA + can only light the cell nucleus of dead cells with green fluorescence after photodynamic therapy, and living cells and dead cells can be clearly distinguished by observing the change of the luminescent color of TPA-3PyA +.)

1. A small molecule self-reporting photosensitizer having the structure shown in formula (I):

2. a method for preparing the photosensitizer of claim 1, comprising the steps of:

(1) carrying out condensation reaction on tri (4-aldehyde biphenyl) amine and 4-pyridine acetonitrile to prepare a condensation product of terphenylamine trivinyl cyanopyridine;

(2) the small molecular self-reporting photosensitizer shown in the formula (I) is finally obtained by carrying out methylation reaction on pyridine by using terphenylamine trivinyl cyanopyridine and methyl iodide.

3. The method according to claim 2, wherein in the condensation reaction of step (1), the molar ratio of tris (4-aldehydiphenyl) amine to 4-pyridineacetonitrile is 1: (3-6).

4. The method according to claim 2, wherein the condensation reaction of step (1) is carried out in an organic solvent; the concentration of the tri (4-aldehyde biphenyl) amine relative to the organic solvent is 0.02-0.05 mmol/mL.

5. The method of claim 2, wherein the condensation reaction of step (1) further comprises adding ammonium acetate and glacial acetic acid.

6. The method of any one of claims 2 to 5, wherein in the reaction of step (2), the molar ratio of the terphenylamine trivinyl cyanopyridine to the methyl iodide is 1 (30-70).

7. Use of the small molecule self-reporting photosensitizer of claim 1 in the preparation of a fluorescent probe for distinguishing between protein and DNA.

8. The use of the small molecule self-reporting photosensitizer of claim 1 in the preparation of an anti-tumor drug.

9. Use of the small molecule self-reporting photosensitizer of claim 1 in the manufacture of a medicament for monitoring cell death in real time.

10. Use of the small molecule self-reporting photosensitizer of claim 1 in the manufacture of a medicament for differentiating between states of cellular activity.

Technical Field

The invention particularly relates to a self-reporting photosensitizer and a preparation method and application thereof, belonging to the technical field of biomedical engineering.

Background

Cancer is the second most fatal disease threatening human life, and nearly 1000 million people die of cancer worldwide in 2020. Nowadays, the precise diagnosis and treatment integration technology has gradually become one of the most attractive research fields in cancer treatment. The integrated optical diagnosis and treatment technology is an advanced non-invasive cancer diagnosis and treatment integrated technology. The technology can simultaneously show good early diagnosis and treatment effects under the excitation of light. Photodynamic therapy, in which imaging is guided, has attracted widespread attention due to its non-invasiveness, traceability and low toxicity. The basic components of photodynamic therapy are light source, photosensitizer and oxygen. When the photosensitizer is excited by a certain light source, the photosensitizer can convert the surrounding oxygen into active oxygen species (such as singlet oxygen) which is toxic to cancer cells, thereby playing a role in killing the cancer cells. However, the conventional phototherapy technology cannot feed back the treatment effect in real time, resulting in problems of treatment delay and over-treatment. Advanced image-guided photodynamic therapy, employing self-reporting photosensitizer systems, has both strong reactive oxygen species generating capacity and good luminescent properties. By utilizing the mode, not only can cancer cells be damaged, but also the photodynamic therapy process can be monitored in situ in real time, so that phototoxicity and other side effects caused by high radiation intensity of illumination and excessive drugs are obviously reduced.

Small molecule compounds are ideal candidates for construction of self-reporting photosensitizers due to their defined composition and good stability. Self-reporting photosensitizers can be used to kill cancer cells and monitor photodynamic therapy processes in real time by conjugating photosensitizers and fluorescent dyes with chemical groups that are sensitive to singlet oxygen to form conjugates. However, the photosensitizer is complex in structure and complicated in preparation process, and is not easy to develop into clinically usable drugs. In addition, the preparation of the small-molecule self-reporting photosensitizer can also realize the capability of tracking the apoptosis process in situ without introducing fluorescent dye. However, such photosensitizers only track the cell death process by observing changes in a single emitted light, and the efficacy of this approach is perturbed by the concentration of the photosensitizer and the intensity of the excitation light.

Disclosure of Invention

The technical problem is as follows: in order to solve the problems that the conventional micromolecule self-reporting photosensitizer tracks the photodynamic therapy process by adopting single emitting light, for example, the visual result of tracking therapy is easily influenced by the concentration of the photosensitizer and the intensity of exciting light, the invention prepares the micromolecule self-reporting photosensitizer capable of emitting double-color light. By observing the dynamic change (luminous color and luminous intensity) of the bicolor light in the treatment process, the interference factors influencing the result in the monochromatic light mode can be avoided, and the diagnosis and treatment integrated effect which is more effective than that in the monochromatic light mode is achieved.

The technical scheme is as follows:

the invention provides a small molecule self-reporting photosensitizer (TPA-3PyA +) with a structure shown in a formula (I):

in one embodiment of the invention, the TPA-3PyA + structurally comprises one twisted Triphenylamine (TPA) unit (electron donor, D), three benzene ring units (pi-bridge), and three cyanovinylpyridine salt (PyA +) units (electron acceptor, a).

The invention also provides a method for preparing the photosensitizer, which comprises the following steps:

(1) carrying out condensation reaction on tri (4-aldehyde biphenyl) amine (compound 1) and 4-pyridine acetonitrile to prepare a condensation product terphenylamine trivinyl cyanopyridine (compound 2);

(2) utilizing terphenylamine trivinyl cyanopyridine and methyl iodide to carry out methylation reaction of pyridine, and finally obtaining the micromolecule self-reporting photosensitizer shown in the formula (I);

in one embodiment of the present invention, in the condensation reaction in step (1), the molar ratio of tris (4-aldehydiphenyl) amine to 4-pyridineacetonitrile is 1: (3-6); specifically, the selection is 1: 4.5.

in one embodiment of the present invention, the condensation reaction in step (1) is carried out in an organic solvent; the organic solvent can be pyridine.

In one embodiment of the present invention, in the step (1), the concentration of tris (4-aldehydiphenyl) amine relative to the organic solvent is 0.02 to 0.05 mmol/mL; specifically, 0.036mmol/mL can be selected.

In one embodiment of the present invention, the condensation reaction in step (1) further comprises adding ammonium acetate and glacial acetic acid.

In one embodiment of the invention, the molar ratio of tris (4-aldehydiphenyl) amine to ammonium acetate is 1: (1-2); the specific choice is 1: 1.

In one embodiment of the invention, the dosage condition of ammonium acetate relative to glacial acetic acid is 0.1-0.3 mmol/mL; specifically, 0.18mmol/mL can be selected.

In one embodiment of the present invention, the temperature of the condensation reaction in step (1) is room temperature (20-30 ℃); the time is 12-30 h.

In one embodiment of the invention, in the reaction in the step (2), the molar ratio of the terphenylamine trivinyl cyanopyridine to the methyl iodide is 1 (30-70); the specific choice is 1: 55.

In one embodiment of the present invention, the reaction in step (2) is carried out using acetone as a solvent.

In one embodiment of the invention, in the reaction in the step (2), the concentration of the terphenylamine trivinyl cyanopyridine relative to the acetone is 2-5 mmol/L; specifically, 2.9mmol/L can be selected.

In one embodiment of the present invention, the reaction in step (2) is carried out at a temperature of 55 to 70 ℃ for a time of 10 to 20 hours.

In one embodiment of the present invention, the reaction of step (2) is carried out under an inert atmosphere. Specifically, the reaction may be carried out under a nitrogen atmosphere.

In one embodiment of the present invention, compound 1 can be prepared by the following method:

tris (4-bromophenyl) amine and 4- (4, 4, 5, 5-tetramethyl-1, 3, 2-dioxaborolan-2-yl) benzaldehyde are used as substrates and undergo a coupling reaction under the catalysis of tetrakis (triphenylphosphine) palladium to prepare a coupling product tris (4-aldehyde biphenyl) amine (compound 1).

In one embodiment of the present invention, the molar ratio of tris (4-bromophenyl) amine to 4- (4, 4, 5, 5-tetramethyl-1, 3, 2-dioxaborolan-2-yl) benzaldehyde in the coupling reaction is 1: (3-6); specifically, 1:3.6 can be selected.

In one embodiment of the invention, the temperature of the coupling reaction is 55-70 ℃ and the time is 20-30 h.

In one embodiment of the invention, the coupling reaction is carried out under an inert atmosphere. Specifically, the reaction may be carried out under a nitrogen atmosphere.

In one embodiment of the present invention, the coupling reaction is performed in a solvent environment; the solvent is a mixed system of tetrahydrofuran and water. Further, the volume ratio of the tetrahydrofuran to the water is (1-4): 1; the specific choice is 3: 1.

In one embodiment of the invention, the amount of the solvent used in the coupling reaction is 10-20mL/mmol relative to tris (4-bromophenyl) amine; specifically, 12mL/mmol can be selected.

In an embodiment of the present invention, the coupling reaction further comprises adding an alkali reagent, wherein the alkali reagent is selected from any one or more of the following: potassium carbonate, sodium carbonate, cesium carbonate.

In one embodiment of the invention, the molar ratio of tris (4-bromophenyl) amine to basic reagent in the coupling reaction is 1 (20-40). Specifically, 1:30 can be selected.

In one embodiment of the present invention, the preparation steps of the photosensitizer specifically include the following:

firstly, mixing tris (4-bromophenyl) amine, 4- (4, 4, 5, 5-tetramethyl-1, 3, 2-dioxaborolan-2-yl) benzaldehyde and a metal catalyst tetrakis (triphenylphosphine) palladium uniformly, and heating to react for 24 hours at 60 ℃ under the protection of nitrogen to obtain a coupling product tris (4-aldehyde biphenyl) amine; uniformly mixing the tri (4-aldehyde biphenyl) amine and 4-pyridine acetonitrile, and reacting at room temperature for 24 hours to generate a condensation product terphenylamine trivinyl cyanopyridine; and finally, uniformly mixing the terphenylamine trivinyl cyanopyridine with iodomethane, reacting for 12 hours at the temperature of 60 ℃ under the protection of nitrogen, and carrying out methylation reaction on the pyridine to finally obtain the micromolecule self-reporting photosensitizer capable of emitting double-color light.

The invention also provides application of the small molecule self-reporting photosensitizer in preparing a fluorescent probe for distinguishing protein from DNA.

The invention also provides application of the small molecule self-reporting photosensitizer in preparation of antitumor drugs.

The invention also provides application of the small molecule self-reporting photosensitizer in preparing a medicament for monitoring cell death in real time.

The invention also provides application of the small molecule self-reporting photosensitizer in preparation of a medicine for distinguishing the activity state of cells.

In one embodiment of the invention, the cell viability status comprises live cells, dead cells.

Has the advantages that:

1. the self-reporting photosensitizer TPA-3PyA + can simultaneously realize photodynamic therapy and real-time monitoring of the light diagnosis and treatment process in a dynamic double-color mode. The self-reporting photosensitizer has high singlet state quantum yield, and the singlet state oxygen quantum yield of the photosensitizer in water is measured to be 124% by taking the photosensitizer bengal as a reference (the singlet state oxygen quantum yield in water is 75%), so that cancer cells can be killed and killed efficiently. The photosensitizer has simple preparation method and obvious anticancer performance, and has certain application prospect in the field of precise cancer treatment.

2. The self-reporting photosensitizer can emit fluorescence with different colors when reacting with protein and DNA, and therefore can be used as a probe for detecting and distinguishing protein and DNA.

3. The photosensitizer TPA-3PyA + of the invention can not only kill cancer cells efficiently, but also enter the cytoplasm of living cells and realize the living cell dyeing of double-color fluorescence. In addition, the emission color, intensity and intracellular localization of TPA-3PyA + can be simultaneously changed with the degree of cell death under continuous light irradiation, so that the TPA-3PyA + can monitor the photodynamic therapy process in situ in real time. More importantly, TPA-3PyA + only brightens the nuclei of dead cells with green fluorescence after photodynamic therapy, indicating that living and dead cells can be clearly distinguished by observing the change in the luminescent color of TPA-3PyA +. The unique optical property of TPA-3PyA + can effectively avoid the interference of tracking cell death by observing the change of fluorescence intensity in the traditional monochromatic mode. The photosensitizer can realize the function of visually tracking the cell death process in real time in a dynamic bicolor mode, and the visual effect of the method is not influenced by the concentration of the photosensitizer and the light intensity of the exciting light.

4. The photosensitizer prepared by the invention can emit fluorescence of different colors after being combined with living/dead cells, so that the identification of the living/dead cells can be realized by simply observing the luminous color of the photosensitizer.

Drawings

FIG. 1 is a schematic diagram of the structure and performance of a small molecule self-reporting photosensitizer TPA-3PyA +.

FIG. 2 is a NMR spectrum of the photosensitizer TPA-3PyA +.

FIG. 3 is the NMR carbon spectrum of the photosensitizer TPA-3PyA +.

FIG. 4 is a high resolution mass spectrum of the photosensitizer TPA-3PyA +.

FIG. 5 is a graph of photoluminescence spectra of the photosensitizer TPA-3PyA + in aqueous solution (containing 1% DMSO) after addition of different concentrations of BSA (0, 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275. mu.g/mL). Excitation wavelength: 488 nm; concentration of TPA-3PyA +: 20. mu. mol/L.

FIG. 6 is a graph showing photoluminescence spectra of the photosensitizer TPA-3PyA + in aqueous solution (containing 1% DMSO) after adding different concentrations of DNA (0, 1, 5,10, 15, 20, 25, 30, 35, 40. mu.g/mL). Excitation wavelength: 488 nm; concentration of TPA-3PyA +: 20. mu. mol/L.

FIG. 7a is the cell survival rate of HeLa cells incubated with different concentrations of the photosensitizer TPA-3PyA + under dark conditions; FIG. 7b shows the cell viability of HeLa cells incubated with different concentrations of the photosensitizer TPA-3PyA +; wavelength range of white light source used: 400 and 800 nm.

FIG. 8 is a two-channel confocal image of the co-culture of the photosensitizer TPA-3PyA + and the live HeLa cells: FIG. 8a is a near infrared light channel imaging diagram (acquisition wavelength range: 600 nm); FIG. 8b is a green light channel imaging diagram (collection wavelength range: 500-600 nm); FIG. 8c is a brightfield view; FIG. 8d is an overlay of the images of FIGS. 8a, 8b and 8 c; excitation wavelength: 488 nm; concentration of TPA-3PyA +: 40 mu mol/L; scale bar: 15 μm.

FIG. 9 is a real-time confocal image of HeLa cells incubated with the photosensitizer TPA-3PyA + under continuous light irradiation: FIGS. 9a-e are diagrams of imaging of cells in the near-infrared light channel at different illumination time points; FIGS. 9f-j are graphs of the imaging of cells at green channel at different illumination time points; FIG. 9k-o is an image of a cell at the light field channel at different illumination time points; excitation wavelength: 488 nm; concentration of TPA-3PyA +: 40 mu mol/L; scale bar: 15 μm.

FIG. 10 is a confocal image of dead HeLa cells after staining with the photosensitizer TPA-3PyA +: FIG. 10a is a green channel image (collection wavelength range: 500-558 nm); FIG. 10b is a near infrared channel image (acquisition wavelength range: > 600nm) and FIG. 10c is a bright field channel image; FIG. 10d is an overlay of the images of FIGS. 10a, 10b and 10 c; excitation wavelength: 488 nm; concentration of TPA-3PyA +: 40 mu mol/L; scale bar: 15 μm.

Detailed Description

Example 1:

preparation route of photosensitizer TPA-3PyA +:

(1) synthesis of Compound 1:

tris (4-bromophenyl) amine (500mg,1.04mmol), 4- (4, 4, 5, 5-tetramethyl-1, 3, 2-dioxaborolan-2-yl) benzaldehyde (868mg,3.74mmol), potassium carbonate (4.30g,31.20mmol), tetrahydrofuran/water (9mL/3mL) and tetrakis (triphenylphosphine) palladium (109mg, 0.094mmol) were charged into a 35mL pressure-resistant reaction flask, and after freezing and deoxygenating with liquid nitrogen, reacted at 60 ℃ for 24 hours under nitrogen protection. After the reaction is finished, cooling to room temperature, removing tetrahydrofuran by rotary evaporation, washing with dichloromethane and water in sequence, drying with anhydrous sodium sulfate, and performing rotary drying on the solvent to obtain a crude product. Column chromatography (eluent: petroleum ether/dichloromethane ═ 1/10, v/v) gave yellow-green compound 1(530mg) in 92% yield.

¹H NMR(400MHz,CDCl₃,ppm)of Compound 1:δ10.05(s,3H,CHO),7.96(d,J＝8.4Hz,6H,ArH),7.76(d,J＝8Hz,6H,ArH),7.61(d,J＝8.8Hz,6H,ArH),7.28(d,J＝8.4Hz,6H,ArH).

(2) Synthesis of Compound 2:

compound 1(0.20g,0.36mmol), 4-pyridineacetonitrile (0.19g,1.62mmol), ammonium acetate (0.028g,0.36mmol), 2mL of glacial acetic acid, and 10mL of pyridine were added to a 50mL round-bottom flask, and the reaction was stirred at room temperature for 24 hours. After the reaction, water was added to the system to precipitate an orange solid. The crude product was collected after suction filtration and washing with water. Column chromatography (eluent: dichloromethane/methanol 45/1, v/v) gave compound 2 as an orange color (0.27g) in 87% yield.

¹H NMR(400MHz,CDCl₃,ppm):δ8.72(dd,J＝1.6Hz,J＝4.8Hz,6H,ArH),8.05(d,J＝8.4Hz,6H,ArH),7.76(s,3H,CH),7.75(d,J＝8.0Hz,6H,ArH),7.63(d,J＝8.4Hz,6H,ArH),7.60(dd,J＝1.6Hz,J＝4.4Hz,6H,ArH),7.30(d,J＝8.8Hz,6H,ArH).¹³C NMR(100MHz,CDCl₃,ppm):δ150.6,147.4,144.6,143.6,142.0,134.4,131.5,130.6,128.2,127.2,124.7,119.9,117.2,108.5.HRMS(ESI):m/z for C₆₀H₄₀N₇ ⁺([M+H]⁺):calc.858.3340；found 858.3401.

(3) Synthesis of the Compound TPA-3PyA +:

compound 2(0.050g,0.058mmol), methyl iodide (0.2mL, 3.2mmol) and acetone (20mL) were added to a 50mL round bottom flask and reacted at 60 ℃ for 12 hours under nitrogen. After the reaction is finished, cooling to room temperature, removing acetone by rotary evaporation, washing the crude product by ethyl acetate and methanol in sequence, and performing suction filtration to obtain a purple black product TPA-3PyA + (0.070g) with the yield of 94%.

¹H NMR(400MHz,DMSO-d₆Ppm) (as shown in figure 2): delta 9.06(d, J ═ 6.8Hz,6H, ArH),8.77(s,3H, CH),8.44(d, J ═ 6.8Hz,6H, ArH),8.23(d, J ═ 8.4Hz,6H, ArH),8.03(d, J ═ 8.4Hz,6H, ArH),7.89(d, J ═ 8.8Hz,6H, ArH),7.28(d, J ═ 8.4Hz,6H, ArH),4.35(s,9H, CH)₃).¹³C NMR(100MHz,DMSO-d₆Ppm) (as shown in FIG. 3): delta 151.0,149.0,147.0,145.8,143.7,133.3,131.5,131.1,128.4,126.9,124.5,123.1,116.5,104.5,47.4.HRMS (ESI) (as shown in FIG. 4): m/z for C₆₃H₄₈N₇ ³⁺([M]³⁺):calc.300.7985；found 300.7984.

Example 2: TPA-3PyA + as fluorescent probe for distinguishing protein and DNA

The photosensitizer TPA-3PyA + structurally consists of a twisted triphenylamine unit (an electron donor, D), three benzene ring units (a bridge) and three cyanovinylpyridine salt units (an electron acceptor, A), and has a twisted D-pi-A structure. The molecule comprises a distorted D-pi-A system, which can endow the molecule with distorted intramolecular charge transfer effect. This effect enables the molecules to have a flexible emission behavior in different media, for example to produce different emission colors and intensities. In addition, the cationic pyridyl group enables TPA-3PyA + to interact with negatively charged biological macromolecules (such as proteins or DNA). The photosensitizer has almost no fluorescence in aqueous solution, and when protein (bovine serum albumin BSA is taken as an example) is added into the system continuously, the near infrared light at 734nm is enhanced continuously (as shown in figure 5). While the green fluorescence at 547nm increased when DNA was added to the system (for example, calf thymus DNA) (as shown in FIG. 6). Therefore, the photosensitizer can be used as a fluorescent probe for distinguishing protein from DNA.

Example 3: photosensitizer (TPA-3PyA +) as anticancer drug

The photosensitizer TPA-3PyA + structurally consists of a twisted triphenylamine unit (an electron donor, D), three benzene ring units (a bridge) and three cyanovinylpyridine salt units (an electron acceptor, A), and has a twisted D-pi-A structure. The D-Pi-A structure can enable molecules to have small singlet-triplet energy gaps, and is beneficial to the generation of singlet oxygen. The photosensitizer was found to have a high singlet oxygen quantum yield (124%) in water, relative to the photosensitizer Bengal red (singlet oxygen quantum yield 75% in water).

Based on this, before examining the killing effect of the photosensitizer on cancer cells, the biocompatibility of the photosensitizer is first examined (as shown in fig. 7 a). Through the classical MTT test, the cancer cells maintain high survival rate (more than 90 percent) after being cultured with different concentrations of the photosensitizer (0 mu mol/L, 10 mu mol/L, 20 mu mol/L, 30 mu mol/L and 40 mu mol/L) for 24 hours in the dark, which indicates that the photosensitizer has good biocompatibility. When the photosensitizer and the cancer cells are cultured for 8 hours and are irradiated by white light with different intensities for 30 minutes (the wavelength range of the white light is 400-800 nm; the intensity is 50 mW/cm)²，70mW/cm²，90mW/cm²) The cell survival rate is continuously reduced along with the increase of the concentration of the photosensitizer and the illumination intensity (as shown in figure 7b), which indicates that the photosensitizer has good anticancer effect and is expected to be an effective photodynamic anticancer drug.

Example 4: photosensitizer (TPA-3PyA +) as medicine for monitoring cell death in real time

In confocal cell imaging, the photosensitizer enters mainly the cytoplasm of the cell and can produce two-color fluorescence (green light and near-infrared light) (see fig. 8). Under continuous blue laser irradiation (wavelength: 488nm), the cell morphology changes, gradually loses integrity, the near infrared light generated by the photosensitizer gradually weakens, the green fluorescence is continuously enhanced, and the location of the photosensitizer in the cell is gradually transferred from the initial cytoplasm to the nucleus, and finally the nucleus is lightened (as shown in FIG. 9). The above shows that the photosensitizer can effectively kill cancer cells under the illumination condition, and can realize real-time tracking of cell death by observing color change, intensity change and intracellular positioning change of double-color fluorescence.

Example 5: photosensitizer (TPA-3PyA +) as medicine for distinguishing living/dead cells

The photosensitizer can effectively contaminate living cells and generate double-color fluorescence (green light and near infrared light), and only generates green fluorescence when contaminating dead cells (as shown in figure 10), so that the photosensitizer can be used as a probe for distinguishing living cells from dead cells.

Comparative example 1 comparison of other different D- π -A type photosensitizers as reported previously

The results are shown in the following table in comparison with other photosensitizers with different structures reported in the prior art.

TABLE 1 comparison of the Performance of different photosensitizers of the D-. pi. -A type