CN108559064B - Conjugated main chain doped zwitterionic polyfluorene vinylene and its preparation and application - Google Patents

Abstract

The invention discloses a zwitterionic water-soluble polyfluorene vinylene doped with a conjugated main chain and its preparation and application. Dibromofluorene derivatives (monomer A), dienyl fluorene derivatives (monomer B), doped with a small amount of narrow band gap dibromoaromatic heterocyclic structure (monomer C), using A+B+C three The method of component polymerization is to carry out the Heck reaction catalyzed by organic metals, and the obtained neutral polymer is then subjected to quaternization and/or carboxylate hydrolysis to obtain a conjugated main chain doped zwitterionic water-soluble polyfluorene vinylene support. The synthesis method is simple, can realize proportional fluorescence emission, and improve detection sensitivity; and can realize red light/near-infrared emission, and improve the effect of fluorescence biological imaging. The zwitterionic structure is conducive to the endocytosis of cells, which can effectively improve the adsorption of materials by the cell membrane, thereby possibly achieving better biological imaging effects.

Description

Conjugated main chain doped zwitterionic polyfluorene vinylene and its preparation and application

technical field

The invention belongs to the technical fields of chemical, biological sensing and fluorescent imaging materials, and in particular relates to a water-soluble zwitterionic water-soluble polymer with alternating fluorene groups and vinyl groups as conjugated main chains and doped with a small amount of aromatic heterocycles Preparation of compounds and their applications in chemical/biosensing, fluorescence bioimaging.

Background technique

In the past ten years, the application of water-soluble conjugated polymers in the fields of information technology such as chemical and biological sensing has attracted more and more extensive and eager attention. These compounds combine the excellent optoelectronic properties of conventional conjugated polymers with the water-solubility of polyelectrolytes. On the one hand, as conjugated polymers, they generally have strong light absorption properties in the ultraviolet and visible region, and have the properties of "molecular wires". On the other hand, they mainly achieve water solubility by attaching hydrophilic ionic functional groups to the side chains of the conjugated system, and the ionic functional groups can interact electrostatically with other charged substances, so they can be quenched by polymers with opposite charges. Electron or energy transfer between quenchers enables highly sensitive detection of various organic, inorganic and biomolecules in the surrounding environment.

Further development on this basis, in recent years, the research and application of water-soluble conjugated polymers as a new type of fluorescent probe material in the field of fluorescence bioimaging has attracted great interest. Chem.Rev. published a review article in 2012 titled "Water-soluble Conjugated Polymers for Fluorescence Imaging, Diagnosis and Therapy", and a large number of research papers on the application of water-soluble conjugated polymers in fluorescence imaging have emerged in various in international authoritative academic journals. Water-soluble conjugated polymers with typical amphiphilic properties can self-assemble in aqueous solution to form nanoparticles, and can also effectively use supramolecular forces such as electrostatic, hydrogen bonding, and hydrophobicity to bind biomolecules or drug molecules to form nanoparticles; Particles can be endocytosed for fluorescence imaging by incubation with cells and further used for in vivo imaging.

At present, most of the water-soluble conjugated polymers that have been used in fluorescence imaging research are ionic functional groups attached to the side chains, and cationic functional groups are attached to the side chains. relatively few. First, the traditional cationic water-soluble conjugated polymer nanoparticles are prone to non-specific protein adsorption when circulating in the body, which affects the accumulation and retention effect in tumor tissue; and when performing fluorescence imaging in cells, there is a difficulty in being absorbed by cells. It is easy to be adsorbed by the cell membrane after endocytosis and endocytosis, because most of the phospholipids inside the cell membrane are negatively charged. Zwitterionic water-soluble conjugated polymers can effectively resist non-specific protein adsorption due to the simultaneous attachment of anions and cations to their side chains, and improve the adsorption of materials by cell membranes, thereby potentially achieving better tumor targeting and bioimaging effects. . Secondly, the zwitterionic polymer structure contains a large number of easily dissociated acidic groups and easily protonated basic groups. The ionization degree of these groups is affected by external conditions such as the pH value of the solution, resulting in The conformation changes accordingly, which leads to changes in the fluorescence spectrum, which can realize the sensing of environmental pH and other factors or fluorescence bioimaging.

Moreover, most of the water-soluble polyfluorene vinylenes studied in the past are polymers formed by two monomers, with a single light-emitting region, most of which are concentrated in the blue light region, and less in the red/near-infrared light region (600–1000 nm). In the red/near-infrared light region, biological tissue absorbs and scatters less light, the penetration ability of light to biological tissue is stronger, and the biological autofluorescence is weaker, which is conducive to the depth detection during in vivo imaging. Therefore, in the present invention, a narrow band gap aromatic heterocycle is introduced into the macromolecular main chain as one of the monomers to obtain a series of zwitterionic water-soluble polyfluorene vinylenes doped with the conjugated main chain. The research results show that the molecular conformation and aggregation state of such polymers can be adjusted by changing external conditions such as solvent, concentration, pH value, resulting in fluorescence resonance energy transfer, thereby exhibiting multiple light-emitting regions, such as 4,7-bis(thiophene) -2-yl)-2,1,3-benzothiadiazole group doped with water-soluble polyfluorene vinylene, which can emit light in the blue and red regions. By comparing the fluorescence emission changes of different light-emitting regions (that is, proportional fluorescence emission), the interference of other factors can be reduced, the detection sensitivity can be improved, and it can be used to design a variety of detection schemes to meet the diverse needs of the detection objects. It has potential broad application prospects in chemical/biosensing and fluorescence bioimaging.

SUMMARY OF THE INVENTION

Technical problem: The purpose of the present invention is to propose a zwitterionic water-soluble polyfluorene vinylene doped with a conjugated main chain and a preparation method thereof, and to propose its application in chemistry, biosensing and fluorescence bioimaging. These material properties can be used to design diverse detection schemes, which can improve detection sensitivity and meet the diverse needs of detection objects, thus making these materials have potential broad application prospects in chemical/biological sensing and fluorescence imaging.

Technical scheme: The zwitterionic water-soluble polyfluorene vinylene doped with the conjugated main chain of the present invention is prepared by organometallic catalyzed Heck polymerization to obtain a neutral polymer, and then quaternized and/or carboxylate The zwitterionic water-soluble polyfluorene vinylene doped with the conjugated main chain is obtained by hydrolysis and other reactions, and the molecular structure of the compound is as follows:

in,

Ar is 4,7-bis(thiophen-2yl)-2,1,3-benzothiadiazole group or 2,5-bis(2-ethylhexyl)-3,6-bis(thiophene-2 base) - one of the diketopyrrolopyrrole groups;

The degree of aggregation n is a natural number greater than 1, x and y are decimals greater than 0 but less than 1, x+y=1, and y≤0.3;

R, R' are not the same and are independently selected from any of the following groups: R ₁ R ₂ R ₃ R ₄ N ⁺ , R ₅ COO ⁻ , R ₁ R ₂ R ₃ R ₆ N ⁺ , or R, R ' is R ₁ R ₂ R ₃ R ₆ N ⁺ at the same time; here R ₁ , R ₂ , R ₃ , R ₄ , R ₅ are one of the following groups: alkyl, alkoxy; R ₆ structural formula is R ₇ SO ₃ ^- , where R ₇ is one of the following groups: alkyl, alkoxy.

in:

a. When Ar is a 4,7-bis(thiophen-2yl)-2,1,3-benzothiadiazole group, two typical structures are as follows:

a1. R and R' are both located at the 9th position of the fluorenyl group, the structure of R is R ₁ R ₂ R ₃ R ₄ N ⁺ , R ₁ is an alkoxy group, and R ₂ , R ₃ and R ₄ are all alkyl groups; The structure of R' is R ₅ COO ^- , R ₅ is an alkyl group, and its structural formula is as follows:

a2. R and R' are both located at the 9th position of the fluorenyl group, R, R' are the structure of R ₁ R ₂ R ₃ R ₆ N ⁺ at the same time, R ₁ is an alkoxy group, and R ₂ and R ₃ are both alkyl groups , the structural formula of R ₆ is R ₇ SO ₃ ^- , where R ₇ is an alkyl group, and its structural formula is as follows:

b. When Ar is a 2,5-bis(2-ethylhexyl)-3,6-bis(thiophen-2yl)-pyrrolopyrrole diketo group, two typical structures are as follows:

b1. Both R and R' are located at the 9th position of the fluorenyl group, the structure of R is R ₁ R ₂ R ₃ R ₄ N ⁺ , R ₁ is an alkoxy group, and R ₂ , R ₃ and R ₄ are all alkyl groups; The structure of R' is R ₅ COO ^- , R ₅ is an alkyl group, and its structural formula is as follows:

b2. Both R and R' are located at the 9th position of the fluorenyl group, R and R' are the structure of R ₁ R ₂ R ₃ R ₆ N ⁺ at the same time, R ₁ is an alkoxy group, and R ₂ and R ₃ are both alkyl groups , the structural formula of R ₆ is R ₇ SO ₃ ^- , where R ₇ is an alkyl group, and its structural formula is as follows:

The preparation method of the zwitterionic water-soluble polyfluorene vinylene doped with the conjugated main chain of the present invention is:

1) adopt the Heck polymerization reaction of organometallic catalysis, first synthesize the neutral conjugated polymer by the method of the three-component polymerization of A+B+C, wherein, A is a dibromofluorene derivative monomer, and B is a diene group Fluorene derivative monomer, C is a dibromo aromatic heterocyclic monomer used for doping,

2) The neutral polymer prepared in step 1) is then subjected to quaternization and/or carboxylate hydrolysis to obtain a zwitterionic water-soluble polyfluorene vinylene doped with a conjugated main chain.

in,

The sum of the amount of species of monomer A and monomer C is equal to the amount of species of monomer B, and the amount of species of C is less than or equal to 30% of the amount of species of B.

The application of the conjugated main chain doped zwitterionic water-soluble polyfluorene vinylene of the present invention in chemical, biological sensing or fluorescent biological imaging.

Beneficial effects: In the present invention, an aromatic heterocycle is introduced into the main chain of polyfluorene vinylene as one of the monomers to obtain a zwitterionic water-soluble polyfluorene vinylene doped with a conjugated main chain. Some external conditions such as pH value can adjust the molecular conformation and aggregation state of the polymer, resulting in fluorescence resonance energy transfer, which shows proportional fluorescence emission in multiple light-emitting regions, and can achieve red/near-infrared emission. . The zwitterionic structure is conducive to the endocytosis of cells, which can effectively improve the adsorption of materials by the cell membrane, thereby possibly achieving better biological imaging effects. These material properties can be used to design diverse detection schemes, which can improve detection sensitivity and meet the diverse needs of detection objects, thus making these materials have potential broad application prospects in chemical/biological sensing and fluorescence imaging.

Description of drawings

Fig. 1 is the UV-Vis absorption spectrum of the zwitterionic water-soluble polyfluorene vinylene prepared by the present invention in water, and the concentration is 2×10 ^-5 mol/L.

Fig. 2 is the fluorescence emission spectrum of the zwitterionic water-soluble polyfluorene vinylene prepared by the present invention in water, and the concentration is 2×10 ^-5 mol/L.

Figure 3. Bright field, dark field and overlay images of the HeLa cell imaging of the zwitterionic water-soluble polyfluorene vinylene prepared by the present invention.

Detailed ways

In order to better understand the content of the present invention, the technical solutions of the present invention are further described below through specific embodiments, but the scope of the present invention cannot be limited by this.

Example 1:

Monomers (1) and (2) were prepared by the following method, (1), (2) and (3) were charged in a material ratio of 1:1.25:0.25, and then were prepared in Pd(OAc) ₂ /P(o -tolyl) ₃ catalyzed by the Heck reaction to couple the three, and after 12 hours of reaction, a neutral 4,7-bis(thiophen-2yl)-2,1,3-benzothiadiazole group was obtained Doping water-soluble polyfluorene vinylene P1; further performing quaternization reaction with iodomethane for 3 days to obtain cationic 4,7-bis(thiophen-2yl)-2,1,3-benzothiadiazole Group-doped water-soluble polyfluorene vinylene P1'; finally, the carboxylate hydrolysis reaction was carried out with trifluoroacetic acid, and the reaction was carried out for 24 hours to obtain zwitterionic 4,7-bis(thiophen-2yl)-2,1,3 - benzothiadiazole group doped water-soluble polyfluorene vinylene P1".

Example 2:

In the same way as in Example 1, monomer (2) was prepared, and monomer (4) was obtained by the following method. Under the catalysis of Pd(OAc) ₂ /P(o-tolyl) ₃ , the three were coupled through Heck reaction, and after 12 hours of reaction, neutral 4,7-bis(thiophen-2yl)-2,1, The 3-benzothiadiazole group was doped with water-soluble polyfluorene vinylene P2, which was further subjected to quaternization reaction with iodomethane for 3 days to obtain cationic 4,7-bis(thiophene-2yl)-2, 1,3-benzothiadiazole group was doped with water-soluble polyfluorene vinylene P2'; finally, 1,4-butane sultone was added to react for 3 days to obtain zwitterionic 4,7-bis( Thiophen-2yl)-2,1,3-benzothiadiazole group-doped water-soluble polyfluorene vinylene P2".

Claims (6)

1. A conjugated main chain doped amphoteric ion type water-soluble polyfluorene vinylene is characterized by having the following molecular formula:

wherein,

ar is one of 4, 7-bis (thiophene-2-yl) -2,1, 3-benzothiadiazole group or 2, 5-bis (2-ethylhexyl) -3, 6-bis (thiophene-2-yl) -pyrrolopyrrole diketone group;

the polymerization degree n is a natural number which is more than 1, x and y are decimal numbers which are more than 0 and less than 1, x + y is 1, and y is less than or equal to 0.3;

r and R' are different and are respectively selected from any one of the following groups: r₁R₂R₃R₄N⁺，R₅COO^-Or R, R' are simultaneously R₁R₂R₃R₆N⁺(ii) a Where R is₁，R₂，R₃，R₄，R₅Are respectively one of the following groups: alkyl, alkoxy; r₆Structural formula is R₇SO₃ ^-Where R is₇Is one of the following groups: alkyl, alkoxy.

2. The conjugated backbone doped zwitterionic water soluble polyfluororenylvinylene of claim 1, wherein:

a. when Ar is a 4, 7-bis (thien-2 yl) -2,1, 3-benzothiadiazole group, two structures selected from:

a1.R and R' are both in the 9-position of the fluorenyl radical, R has the structure R₁R₂R₃R₄N⁺，R₁Is alkoxy, R₂、R₃And R₄Are all alkyl; the structure of R' is R₅COO^-，R₅Is an alkyl group having the formula:

a2.R and R 'are both in the 9-position of the fluorenyl radical, R, R' are both R₁R₂R₃R₆N⁺Structure of (1), R₁Is alkoxy, R₂And R₃Are each alkyl, R₆Structural formula is R₇SO₃ ^-Where R is₇Is an alkyl group having the formula:

3. the conjugated backbone doped zwitterionic water soluble polyfluororenylvinylene of claim 1, wherein:

b. when Ar is a2, 5-bis (2-ethylhexyl) -3, 6-bis (thien-2-yl) -pyrrolopyrroledione group, two structures selected from:

b1.R and R' are both in the 9-position of the fluorenyl radical, the structure of R being R₁R₂R₃R₄N⁺，R₁Is alkoxy, R₂、R₃And R₄Are all alkyl; the structure of R' is R₅COO^-，R₅Is an alkyl group having the formula:

b2.R and R 'are both in the 9-position of the fluorenyl radical, R and R' are both R₁R₂R₃R₆N⁺Structure of (1), R₁Is alkoxy, R₂And R₃Are each alkyl, R₆Structural formula is R₇SO₃ ^-Where R is₇Is an alkyl group having the formula:

4. a method for preparing the zwitterionic water-soluble polyfluororenylvinylene doped with the conjugated main chain according to claim 1, 2 or 3, which is characterized by comprising the following steps:

1) synthesizing neutral conjugated polymer by adopting organic metal catalyzed Heck polymerization reaction and a three-component polymerization method of A + B + C, wherein A is a dibromofluorene derivative monomer, B is a dienylfluorene derivative monomer, C is a dibromoaromatic heterocyclic monomer for doping,

2) and (2) carrying out quaternary ammonification and carboxylic ester hydrolysis reaction or quaternization and sulfonic ester hydrolysis reaction on the neutral polymer prepared in the step 1) to obtain the conjugated main chain doped zwitterionic water-soluble polyfluorene vinylene.

5. The method for preparing a conjugated main chain doped zwitterionic water-soluble polyfluororenylene as claimed in claim 4, wherein the sum of the amounts of the substances of monomer A and monomer C is equal to the amount of the substance of monomer B, and the amount of the substance of C is less than or equal to 30% of the amount of the substance of B.

6. Use of the conjugated backbone doped zwitterionic water soluble polyfluorene vinylene of claim 1 in chemical sensing, biosensing or fluorescence bioimaging.

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