CN103951805B - the preparation method and application of star polymer - Google Patents

Abstract

The invention relates to a preparation method and application of a novel cationic amphiphilic four-arm star polymer. Specifically, the star polymer can be obtained by synthesis methods such as atom transfer radical polymerization (ATRP) and click chemistry. Wherein the core of the star-shaped polymer is tetraphenylethylene with aggregation-induced luminescent properties; the linear arm of the polymer is a cationic amphiphilic random copolymer with excellent antibacterial effect _; covalently labeled T1 type magnetic resonance ( MR) contrast agents are organic gadolinium chelates. By using the cationic amphiphilic four-armed star polymer, the present invention realizes the double quantitative detection of fluorescence/magnetic resonance of negatively charged Gram-positive and negative bacteria on the surface in a pure water environment; antibacterial effect.

Description

Preparation method and application of star polymer

technical field

The present invention relates to the preparation and application of star polymers, more specifically, to the preparation and application of a cationic amphiphilic four-arm star polymer.

Background technique

Infectious diseases, especially infections caused by pathogenic bacteria, are currently one of the main causes of human death worldwide (Anthony S. Fauci, et al. N. Engl. J. Med. 2012, 366, 454-461). The development of new materials or methods for rapid and efficient bacterial detection and antibacterial is an effective way to meet this challenge. On the one hand, although the bacterial detection methods based on plate culture, immunoassay, and electrochemistry have their own advantages, they are often accompanied by disadvantages such as long analysis time, complicated experimental operations, and high cost (F.Javier Del Campo, et al. Biosens. Bioelectron. 2007, 22, 1205-1217). However, whole-cell bacterial detection methods based on magnetic resonance, Raman scattering, surface plasmon resonance, etc. usually do not involve complex cell lysis and biomarker extraction operations, so the time-consuming is relatively short. The detection of whole-cell bacteria combined with fluorescence analysis, in addition to being easy to operate and short in time, also has the advantages of high sensitivity and low instrument cost (S.Wang, et al.Angew.Chem.Int.Ed. 2011, 50, 9607-9610). Meanwhile, due to its special properties, multimodal imaging has received more and more attention in recent years. Combined with the high sensitivity of fluorescence detection and the deep penetration of soft tissue of magnetic resonance detection, a multimodal system that can simultaneously realize dual detection of fluorescence and magnetic resonance has potential application value (Ick Chan Kwon, et al.Chem.Soc.Rev .2012, 41, 2656-2672).

On the other hand, in the process of humans resisting pathogenic bacteria, compared with the currently widely used small molecule antibiotics, antimicrobial peptides and artificial synthetic mimics derived from the natural immune system are generally believed to destroy the bacterial cell membrane structure through physical action As a result, the contents of bacterial cells leak and die, so this mechanism will not cause bacterial drug resistance. At the same time, artificial synthetic macromolecular antibacterial agents have advantages that natural antibacterial peptides cannot match due to their cheap raw materials and abundant sources, diverse and simple preparation processes, and adjustable properties (Y. Yang, et al. Nano Today 2012, 7, 201-222); the amphiphilic cationic polymers that have been extensively studied in recent years are the representative ones.

Due to the ability to track biodistribution and evaluate therapeutic effects in real time, one of the current research hotspots in the field of tumor therapy is to develop a multifunctional system with both detection and treatment functions (Andrew Tsourkas, et al. Science 2012, 338, 903-910). In terms of combating pathogenic bacteria, such multifunctional systems have rarely been discovered so far. By integrating fluorescence/magnetic resonance dual detection with macromolecular antibacterial agents into a multifunctional system, it should have potential and important biological applications.

Contents of the invention

The purpose of the present invention is to simultaneously realize the dual fluorescence/magnetic resonance detection and antibacterial effect of bacteria in a pure water environment. Therefore, a preparation method of a kind of cationic amphiphilic four-arm star polymer is provided.

In one aspect of the invention there is provided a star polymer of formula I,

Wherein -L ₁ to -L ₄ each independently have the following structure:

Wherein W is a linear linking group with 1-50 carbon atoms and 1-5 heteroatoms selected from N, S, O,

Wherein V has 3-50 carbon atoms, preferably 5-40 carbon atoms, more preferably 7-30 carbon atoms, more preferably 10-20 carbon atoms, ^1-5 selected from N, S, O Heteroatoms, preferably 1-3 nitrogen atoms and oxygen atoms, more preferably 1 nitrogen atom and 2 oxygen atoms, and contain cations, preferably N cation repeating units, wherein V ² has 3-50 carbon atoms, preferably 5 -40 carbon atoms, more preferably 7-30 carbon atoms, more preferably 10-20 carbon atoms, 1-5 hydrophobic repeating units selected from N, S, O heteroatoms, preferably 5-15 nitrogen atoms And oxygen atoms, preferably 8 nitrogen atoms and 10 oxygen atoms, ^V3 has 3-100 carbon atoms, preferably 5-80 carbon atoms, more preferably 10-50 carbon atoms, more preferably 20-40 carbon atoms Atoms, 1-20 heterogens selected from N, S, O, preferably 5-15 nitrogen atoms and oxygen atoms, more preferably 8 nitrogen atoms and 10 oxygen atoms, and repeating units containing coordinated metal atoms ;and

Wherein n=5～50; x=0%～99%, y=0%～99%, and satisfy 90%≤x+y≤99%; and z=1%～10%;

wherein L ₁ to L ₄ are different from each other, or 2 to 4 of L ₁ to L ₄ are identical to each other; and/or

The number average molecular weights of L ₁ to L ₄ are each independently 10 ³ to 10 ⁴ , and/or the molecular weight distributions of L ₁ to L ₄ are each independently 1 to 10.

In one embodiment of the invention, V ¹ to V ³ comprise partial structures as shown below:

Wherein X ¹ is H or CH ₃ ; * represents the position connected with the rest of V ¹ to V ³ .

In ^one embodiment of the invention V comprises a partial structure selected from the group consisting of:

In one embodiment of the invention, V ² comprises a partial structure selected from the group consisting of:

C ₁ -C ₅ alkyl.

In one embodiment of the invention ^V3 comprises a partial structure selected from the group consisting of:

Wherein Z is _a divalent linking group having 1-50 carbon atoms and 1-5 heteroatoms selected from N, S, O.

In one embodiment of the invention Z is _a partial structure selected from the group consisting of:

where * is the attachment position to the polymer backbone, where ** is the attachment position to the -NH- linking group in the metal complex.

In one embodiment of the invention, W is

_{In one} embodiment of the present invention, L to L are each independently a product of atom transfer radical polymerization of a radically polymerizable monomer; the radically polymerizable monomer is, methacrylic acid shrinkage At least one of glyceride, dimethylaminoethyl methacrylate and methacrylic acid monomer or alkyl acrylate monomer.

In another aspect of the present invention, there is provided a method for preparing a star polymer, the method comprising the steps of:

i) using a complex formed by a multidentate nitrogen compound and a transition metal halide as a catalyst system, and using a compound of the structure shown in formula A as an initiator, carry out atom transfer radical polymerization to obtain a linear polymer arm of a star polymer, Wherein, the polymerization reaction is random copolymerization of glycidyl methacrylate and at least one of dimethylaminoethyl methacrylate and alkyl ester monomers,

Formula A:

Among them, n=1～10;

ii) The alkyne-terminated linear polymer prepared in the step i) is the arm of a star polymer, and reacted with the structural compound shown in formula B to obtain a four-arm star polymer,

Formula B:

Among them, n=1～10;

iii) Using the four-armed star polymer prepared in step ii) as a precursor, through the reaction of sodium azide and glycidyl ester residues, azide groups are introduced into the linear polymer arms, and then click The chemical reaction bonds the organometallic compound; the tertiary amine is then quaternized with a proton or a haloalkane.

The invention simultaneously realizes the purpose of utilizing the cationic amphiphilic four-armed star polymer as a bacterial fluorescence/magnetic resonance dual detection probe and a macromolecule antibacterial agent.

Description of drawings

FIG. 1 shows the chemical structural formula of a four-armed star polymer S1 according to one embodiment of the present invention.

FIG. 2 shows the infrared absorption spectrum of the four-armed star polymer S1 according to one embodiment of the present invention.

Figure 3 shows the gel permeation chromatography (tetrahydrofuran as mobile phase) of the four-arm star polymer S1 according to one embodiment of the present invention.

FIG. 4 shows the change of the fluorescence emission spectrum of the star polymer S1 according to one embodiment of the present invention with the increase of the concentration of Escherichia coli.

Fig. 5 shows the variation of the maximum fluorescence emission peak intensity of the star polymer S1 according to one embodiment of the present invention with the increase of the concentration of Escherichia coli.

FIG. 6 shows confocal laser micrographs of the staining effect of star polymer S1 on Escherichia coli according to one embodiment of the present invention.

Fig. 7 shows the change of the longitudinal relaxation rate signal of the star polymer S1 according to one embodiment of the present invention with the increase of the concentration of Escherichia coli.

Fig. 8 shows the change of the gray scale contrast of the magnetic resonance signal of the star polymer S1 according to an embodiment of the present invention with the increase of the concentration of Escherichia coli.

Fig. 9 shows the relationship between the antibacterial effect of the star polymer S1 on Escherichia coli and the concentration of the polymer according to one embodiment of the present invention.

Fig. 10 shows a scanning electron micrograph of the effect of the star polymer S1 on the morphology of Escherichia coli according to one embodiment of the present invention.

Fig. 11 shows the relationship between the antibacterial effect of the star polymer S1 on Staphylococcus aureus and the concentration of the polymer according to one embodiment of the present invention.

Fig. 12 shows the variation of the maximum fluorescence emission peak intensity of the star polymer S4 according to one embodiment of the present invention with the increase of the concentration of Escherichia coli.

Fig. 13 shows the relationship between the antibacterial effect of the star polymer S4 on Escherichia coli and the concentration of the polymer according to one embodiment of the present invention.

detailed description

In one aspect, the present invention provides a cationic amphiphilic four-arm star polymer, characterized in that the amphiphilic four-arm star polymer is formed by atom transfer radical polymerization (ATRP) and click chemistry (Click chemistry) ) and other modified means are obtained, and the star-shaped polymer structure is shown in formula I,

Formula I:

Wherein, p=1-10; q=1-10; m=0-5; n=5-50; x=0%-99%; y=0%-99%; z=1%-10%.

In another aspect, the present invention provides the use of the above-mentioned four-armed star polymer as a bacterial fluorescence detection probe.

In another aspect, the present invention provides the application of the above-mentioned four-armed star polymer as a probe for the detection of bacterial magnetic resonance.

In another aspect, the present invention provides the use of the above-mentioned four-armed star polymer as a macromolecular antibacterial agent.

The present invention will be further described below in conjunction with specific examples, but the present invention is not limited to the following examples.

Preparation example 1.

In the first step, the following cationic amphiphilic linear copolymer L1 is prepared:

It is characterized in that: while the end group is an alkynyl group, it contains a positively charged tertiary amine monomer, a hydrophobic long alkyl chain monomer, and a glycidyl ester monomer that can be modified by sodium azide.

Preparation method: use polydentate nitrogen ligand and transition metal halide as catalyst, propynyl bromoisobutyrate as initiator, dimethylaminoethyl methacrylate, n-butyl methacrylate, shrink methacrylate Glyceride is a monomer, undergoing atom transfer radical random copolymerization. Proynyl bromoisobutyrate (25mg, 0.13mmol), dimethylaminoethyl methacrylate (1.63g, 10.4mmol), n-butyl methacrylate (0.08g, 0.56mmol), glycidyl methacrylate Esters (50mg, 0.35mmol), pentamethyldiethylenetriamine (41mg, 0.23mmol) were dissolved in anisole (2mL), fully degassed and equilibrated at 40°C for 10 minutes, then cuprous bromide (16mg , 0.11 mmol). Polymerization was terminated after 4 hours and precipitated three times in diethyl ether after removal of metal salts. After vacuum drying, a white solid product was obtained (0.76 g, yield ~43%; GPC test results using tetrahydrofuran as mobile phase: number average molecular weight M _n =4.3 kDa, molecular weight distribution M _w /M _n =1.2).

In the second step, the following amphiphilic four-armed star polymer S0 is prepared:

It is characterized in that it is a four-armed star-shaped polymer with tetraphenylethylene as the core and tertiary amine, long-chain alkyl and propylene oxide groups as side chains.

Preparation method: use polydentate nitrogen ligands and transition metal halides as catalysts to catalyze the click chemical reaction between 4-azidoethoxy-modified tetraphenylethylene derivatives and L1. 4-azidoethoxy-modified tetraphenylethylene derivatives (16.8 mg, 1 equivalent of azide group), L1 (2.7 g, 8 equivalents of alkynyl group), pentamethyldiethylenetriamine ( 138mg, 8 times equivalent) was dissolved in N,N-dimethylformamide (50mL), after fully degassed, cuprous bromide (114mg, 8 times equivalent) was added, and the reaction was started at 50°C. Azide-modified Merrifield resin (20 equivalents of azide groups) was added after 48 hours. After continuing to react at 50°C for 48 hours, the reaction was stopped, and the resin and metal salts were removed by filtration, and then precipitated three times in ether. After vacuum drying, a white solid product was obtained (1.01 g, yield ~74%; GPC test results using tetrahydrofuran as mobile phase: number average molecular weight M _n =22.0 kDa, molecular weight distribution M _w /M _n =1.3).

The third step is to prepare the following amphiphilic four-armed star polymer S1:

It is characterized in that it is a four-armed star-shaped polymer with tetraphenylethylene as the core and containing positively charged tertiary amines, long-chain alkyl groups, and T1 _- type magnetic resonance contrast agent groups as side chains.

Preparation method: firstly, in the presence of ammonium chloride, sodium azide is used to open the epoxy group of the above-mentioned SO, and introduce the azide group to the side chain of the four-armed star polymer. SO (256mg, 1 times equivalent epoxy group), sodium azide (20mg, 3 times equivalents), ammonium chloride (17mg, 3 times equivalents) was dissolved in N, N-dimethylformamide (5mL), The reaction was completed after 24 hours at 50°C. After filtration, dialysis, and lyophilization, a white solid product (228 mg, yield ~ 88%; GPC test results using tetrahydrofuran as the mobile phase: number average molecular weight M _n = 22.1 kDa, molecular weight distribution M _w /M _n = 1.3). The azidated star polymer was then subjected to a click chemistry reaction with the alkyne _- modified T1 contrast agent DOTA-Gd in the presence of a transition metal catalyst. Azidated star polymer (280 mg, 1 equivalent of azide group), alkynylated DOTA-Gd (120 mg, 2 equivalents), pentamethyldiethylenetriamine (35 mg, 2 equivalents), Dissolve in N,N-dimethylformamide (5 mL) and add cuprous bromide (29 mg, 2 equivalents) after fully degassed. Stop the reaction after reacting at 50°C for 24 hours, remove the copper salt, dialyze and freeze-dry to obtain the white solid product S1 (270 mg, yield ~ 80%; the test result using tetrahydrofuran as the mobile phase is: number average molecular weight _Mn = 24.4kDa , molecular weight distribution M _w /M _n = 1.4; Fourier transform-infrared absorption characteristic peaks are: 1729cm ^-1 , 1615cm ^-1 , 1585cm ^-1 , 1505cm ^-1 , 1459cm ^-1 , 1387cm ^-1 , 1269cm ^-1 , 1222cm ^-1 , 1159cm ^-1 , 1125cm ^-1 , 1075cm ^-1 , 1037cm ^-1 , 944cm ^-1 , 800cm ^-1 ).

Preparation example 2.

In the first step, the following amphiphilic linear copolymer L2 is prepared:

It is characterized in that: while the end group is an alkynyl group, it contains a positively charged tertiary amine monomer, a hydrophobic long alkyl chain monomer, and a glycidyl ester monomer that can be modified by sodium azide.

Preparation method: similar to the preparation method in Preparation Example 1, adjusting the feed ratio of monomers participating in atom transfer radical polymerization (ATRP). Dissolve propynyl bromoisobutyrate, dimethylaminoethyl methacrylate, n-butyl methacrylate, glycidyl methacrylate, and pentamethyldiethylenetriamine in anisole in turn. After degassing, equilibrate at 40°C for 10 minutes, then quickly add cuprous bromide. After 4 hours, the polymerization was terminated, the metal salt catalyst was removed, concentrated, and precipitated three times in diethyl ether. After vacuum drying, a white solid product was obtained (0.54 g, yield ~40%; GPC test results using tetrahydrofuran as mobile phase: number average molecular weight M _n =4.6 kDa, molecular weight distribution M _w /M _n =1.2).

In the second step, the following amphiphilic four-arm star polymer S2 is prepared:

It is characterized in that it is a four-armed star-shaped polymer with tetraphenylethylene as the core and containing positively charged tertiary amines, long-chain alkyl groups, and T1 _- type magnetic resonance contrast agent groups as side chains.

Preparation method: First, use pentamethyldiethylenetriamine and cuprous bromide as catalysts to catalyze the click chemical reaction between 4-azidoethoxy-modified tetraphenylethylene derivatives and L2. Then sodium azide was used to open the epoxy group and introduce the azide group to the side chain of the four-armed star polymer. The azidated star polymer and the alkyne _- modified T1 contrast agent were subjected to a click chemical reaction in the presence of a cuprous bromide catalyst; after purification and freeze-drying, a white solid product S2 (220 mg, yield ~ 75%; the test results using tetrahydrofuran as the mobile phase are: M _n = 19.2kDa, M _w /M _n = 1.4; Fourier transform-infrared absorption characteristic peaks are: 1727cm ^-1 , 1613cm ^-1 , 1583cm ^-1 , 1507cm ^-1 , 1461cm ^-1 , 1381cm ^-1 , 1267cm ^-1 , 1225cm ^-1 , 1157cm ^-1 , 1123cm ^-1 , 1073cm ^-1 , 1035cm ^-1 , 946cm ^-1 , 798cm ^-1 ).

Preparation example 3.

In the first step, the following linear copolymer L3 is prepared:

It is characterized in that: while the end group is an alkynyl group, it contains a positively charged tertiary amine monomer and a glycidyl ester monomer that can be modified by sodium azide.

Preparation method: similar to the preparation method in Preparation Example 1, adjusting the feed ratio of monomers participating in atom transfer radical polymerization (ATRP). Propynyl bromoisobutyrate, dimethylaminoethyl methacrylate, glycidyl methacrylate, and pentamethyldiethylenetriamine were dissolved in anisole in turn for atom transfer radical polymerization (ATRP) . After 4 hours, the polymerization was terminated, and the metal salt catalyst was removed, followed by concentration and precipitation. After vacuum drying, a white solid product was obtained (0.68 g, yield ~52%; GPC test results using tetrahydrofuran as mobile phase: number average molecular weight M _n =3.8 kDa, molecular weight distribution M _w /M _n =1.3).

In the second step, the following four-arm star polymer S3 is prepared:

It is characterized in that it is a four-armed star-shaped polymer with tetraphenylethylene as the core, a positively charged tertiary amine, and a T1 _- type magnetic resonance contrast agent group as the side chain.

Preparation method: First, use pentamethyldiethylenetriamine and cuprous bromide as catalysts to catalyze the click chemical reaction between 4-azidoethoxy-modified tetraphenylethylene derivatives and L3. Then sodium azide was used to open the epoxy group and introduce the azide group to the side chain of the four-armed star polymer. The azidated star polymer and the alkyne _- modified T1 contrast agent were subjected to a click chemical reaction under the catalysis of monovalent copper; after purification and freeze-drying, a white solid product S3 (250 mg, yield ~ 78%; The test results using tetrahydrofuran as the mobile phase are: number average molecular weight M _n = 21.2kDa, molecular weight distribution M _w /M _n = 1.4; Fourier transform-infrared absorption characteristic peaks are: 1729cm ^-1 , 1630cm ^-1 , 1465cm ^{- 1} , 1402cm ^-1 , 1272cm ^-1 , 1240cm ^-1 , 1158cm ^-1 , 1083cm ^-1 , 984cm ^-1 , 921cm ^-1 , 855cm ^-1 , 799cm ^-1 ).

Preparation example 4.

The following cationic amphiphilic four-armed star polymer S4 was prepared:

It is characterized in that it is a four-armed star-shaped polymer with tetraphenylethylene as the core and positively charged quaternary ammonium, long-chain alkyl, and T1 _- type magnetic resonance contrast agent groups as side chains.

Preparation method: Dissolve the four-armed star-shaped polymer (240 mg) obtained in Preparation Example 1 in dimethyl sulfoxide (10 mL), add excess ethyl bromide (2 mL), and react at 40°C for 3 days to stop the reaction. Concentrated under reduced pressure, dialyzed and freeze-dried to obtain the white solid product S4 (360 mg, yield ~92%). Potentiometric titration experiments demonstrated a quaternization efficiency of -100%.

Application Example 1: S1 Star Polymer as a Bacterial Fluorescent Probe

The amphiphilic four-armed star polymer prepared by the above method is based on tetraphenylethylene with aggregation-induced luminescent properties, when it is adsorbed into the water environment by supramolecular interactions (electrostatic attraction, hydrophobic interaction, etc. When the negatively charged bacterial surface is exposed, its optical properties change dramatically. As shown in Figure 4, when excited by 360nm ultraviolet light, the fluorescence emission intensity of the cationic amphiphilic four-armed star polymer S1 gradually increases with the increase of the concentration of Escherichia coli in the aqueous solution. Through quantitative calculation, it can be seen that within a certain range, the intensity of the maximum fluorescence emission peak of S1 at 475 nanometers increases linearly with the increase of the concentration of E. coli ( FIG. 5 ). Compared with the blank control, when 4.5*10 ⁷ CFU/mL Escherichia coli was added, the fluorescence was enhanced by 7.64 times. As shown in Figure 6, when Escherichia coli cells were co-cultured with the amphiphilic four-arm star polymer S1 for a certain period of time, confocal laser fluorescence microscopy (excitation wavelength: 405 nm; fluorescence reception wavelength: 423-503 nm; 63 Under the same conditions, it can be observed that E. coli cells are stained as blue-green fluorescence; while under the same conditions, E. coli cells that have not been stained by SI have no similar luminescent phenomenon. This shows that the cationic amphiphilic four-armed star polymer S1 can indeed limit the rotation strength of the tetraphenylethylene aromatic ring in the inner core of the star polymer to a great extent after being adsorbed on the bacterial cell surface through supramolecular interactions, Inhibit its energy dissipation pathway due to intramolecular rotation and enhance its energy dissipation pathway caused by fluorescence emission, thereby causing changes in optical properties. Using this optical signal change process, the fluorescence quantitative detection of bacteria in the water environment can be realized.

Application Example 2: S1 star polymer as a bacterial magnetic resonance probe

The linear polymer arm structure of the amphiphilic four-armed star polymer prepared by the above method is covalently labeled with T1 _- type magnetic resonance contrast agent organogadolinium chelate. When the amphiphilic four-armed star polymer binds to the surface of bacteria showing electronegativity through supramolecular forces such as electrostatic attraction and hydrophobic interaction, the T1 _- type magnetic resonance contrast agent organic gadolinium chelate affects the longitudinal relaxation of water protons. The relaxation time and longitudinal relaxation rate can vary greatly. As shown in Figure 7, when in a 1.5T magnetic field, with the gradual increase of the concentration of Escherichia coli in the aqueous solution, the longitudinal relaxation time of the water protons containing the amphiphilic four-armed star polymer S1 gradually shortens, and the longitudinal relaxation rate gradually decreases. Increase. Compared with the blank control, when 1*10 ⁷ CFU/mL E. coli was added, 1/T ₁ had an increase of ~0.58s ^-1 . As shown in Figure 8, in a 1.5T magnetic field, TR is 600 milliseconds, and TE is 9 milliseconds, gradually increasing the concentration of Escherichia coli, it can be seen that the contrast of the T ₁ MRI signal is gradually enhanced—the same as that shown in Figure 7 The results are consistent. This shows that the cationic amphiphilic four-armed star polymer S1 can effectively increase the rotation correlation time of the organic gadolinium chelate of the T ₁ type magnetic resonance contrast agent when it is adsorbed to the surface of bacteria through supramolecular interactions, thereby shortening the time associated with it. The longitudinal relaxation time of the water protons undergoing exchange increases its longitudinal relaxation rate. Using this magnetic resonance signal change, the magnetic resonance quantitative detection of bacteria in the water environment can be realized.

Application example 3: S1 star polymer as a macromolecular antibacterial agent

The main chemical composition of the linear arm structure of the amphiphilic four-arm star polymer prepared by the above method is a positively charged tertiary amine group and a lipophilic long-chain alkyl group. As a typical polycationic amphiphilic macromolecular antibacterial agent, when the four-armed star polymer is adsorbed on the surface of bacterial cells through its own supramolecular interaction with bacterial cells, the linear arms of the polycationic amphiphilic macromolecules will further develop in the bacterial cell surface. The surface of the bacterial cell is perforated, causing the destruction of the bacterial cell membrane structure, resulting in the leakage of the bacterial cell content, thereby achieving the antibacterial effect. As shown in Figure 9, as the concentration of the amphiphilic four-armed star polymer S1 in the aqueous solution gradually increased, its bacteriostatic effect gradually increased. The minimum inhibitory concentration (MIC) of the amphiphilic four-armed star polymer S1 was 5.5 mg/L, showing good antibacterial effect. Further, as shown in Figure 10, after co-cultivating with the amphiphilic four-armed star polymer S1 for 2 hours, it can be found under the scanning electron microscope that, compared with the control group, the surface of E. coli cells in the experimental group appeared More obvious wrinkles and deformations, and more serious intertwining and cross-linking between cells. This shows that the amphiphilic four-arm star polymer S1 prepared by the above method mainly achieves the antibacterial effect by destroying the rigidity and integrity of the bacterial cell membrane. Similarly, the antibacterial experiment against Gram-positive bacteria Staphylococcus aureus has also obtained good experimental results (Figure 11). When the S1 concentration increased to 10 mg per liter, the relative survival rate of Staphylococcus aureus was less than 20%. .

Application Example 4: S4 Star Polymer as a Bacterial Fluorescent Probe

The fluorescence emission intensity of the cationic amphiphilic four-armed star polymer S4 gradually increased with the increase of the concentration of E. coli in the aqueous solution. Through quantitative calculation, it can be seen that within a certain range, the intensity of the maximum fluorescence emission peak of S4 at 475 nanometers increases linearly with the increase of the concentration of E. coli ( FIG. 12 ). Compared with the blank control, when 9*10 ⁷ CFU/mL Escherichia coli was added, the fluorescence was enhanced by 3.17 times; at the same time, within a certain range, there was a good linear relationship between different bacterial concentrations and the corresponding maximum fluorescence emission intensity. It shows that the cationic amphiphilic copolymer S4 can also realize the fluorescence quantitative detection of bacteria in the water environment.

Application example 5: S1 star polymer as a macromolecular antibacterial agent

As shown in Figure 13, as the concentration of the amphiphilic four-armed star polymer S4 in the aqueous solution gradually increased, its antibacterial effect gradually increased, and when the polymer concentration was greater than 10 mg per liter, the antibacterial effect was significantly enhanced. The minimum inhibitory concentration (MIC) of the cationic amphiphilic four-armed star polymer S4 was 11 mg/L, showing good antibacterial effect.

The present invention has been described in detail above, but the present invention is not limited to the specific embodiments described herein. Those skilled in the art understand that other changes and modifications can be made without departing from the scope of the present invention. The scope of the invention is defined by the appended claims.

Claims (8)

1. the star-type polymer of Formulas I,

Wherein-L₁To-L₄Have a structure that independently of one another

Wherein W be have 1-50 carbon atom and 1-5 selected from N, S, O heteroatomic linearly Linking group,

Wherein V¹For having 3-50 carbon atom, 1-5 the hetero atom selected from N, S, O, and Containing the repetitive of cation, wherein V²That there is 3-50 carbon atom, 1-5 selected from N, S, The heteroatomic hydrophobic recurring units of O, V³That there is 3-100 carbon atom, 1-20 selected from N, The hetero atom of S, O, and the repetitive containing the metallic atom being coordinated；And

Wherein n=5～50；0% ＜ x≤99%, 0% ＜ y≤99%, and meet 90%≤x+y≤99%； And z=1%～10%；

Wherein L₁To L₄It is different from each other, or L₁To L₄In 2 to 4 be mutually the same 's；And/or

Wherein L₁To L₄Number-average molecular weight be each independently 10³～10⁴, and/or L₁To L₄Point Son amount distribution is each independently 1～10；

Wherein V¹Comprise the part-structure of group selecting free the following to form:

Wherein V³Comprise the part-structure of group selecting free the following to form:

Wherein Z₁It is that there is 1-50 carbon atom, 1-5 the heteroatomic bivalence selected from N, S, O Linking group.

Star-type polymer the most according to claim 1, wherein V¹To V³Comprise as follows Part-structure:

Wherein X¹For H or CH₃；* represent and V¹To V³In remaining part connect position.

Star-type polymer the most according to claim 1, wherein V²Comprise the free the following of choosing The part-structure of the group of composition:

C₁-C₅Alkyl.

Star-type polymer the most according to claim 1, wherein Z₁It is to select free the following group The part-structure of the group become:

Wherein * is the link position with main polymer chain, wherein * * and-NH-in metal complex The link position of linking group.

Star-type polymer the most according to claim 1, wherein W is

6. according to the star-type polymer described in any one in claim 1 to 5, wherein L₁To L₄ The monomer being each independently free redical polymerization carries out the product of atom transfer radical polymerization；Described The monomer that can carry out radical polymerization is, glycidyl methacrylate and dimethylaminoethyl acrylate methyl ammonia Base ethyl ester and at least one in methacrylic acid monomer or alkyl-acrylates monomer.

7. the method preparing star-type polymer, described method comprises the steps:

I) complex formed with multiple tooth nitrogen compound and transition metal halide is as catalyst system and catalyzing, with formula Structural compounds shown in A is initiator, carries out atom transfer radical polymerization, obtains star polymer Linear polymer arm, wherein, described polyreaction is dimethylaminoethyl methacrylate and methyl Acrylic acid contracting art glyceride and optional alkyl-acrylates monomer carry out random copolymerization,

Formula A:

Wherein, n=1～10；

Ii) the end alkynyl radical linear polymer prepared with the described step i) arm as star polymer, with Structural compounds shown in formula B reacts, and obtains four arm star polymers,

Formula B:

Wherein, n=1～10；

Iii) with described step ii) the four arm star polymers that prepare as precursor, pass through Hydrazoic acid,sodium salt With the reaction of ethylene oxidic ester residue, linear polymeric arms introduces azido group, then by clicking on The T that chemical reaction bonding alkynyl is modified₁Contrast agent DOTA-Gd；Then proton or halogenated alkane are utilized Tertiary amine is carried out quaterisation.

8. according to the polymer described in any one in claim 1-6 for bacterial fluorescence probe, thin Bacterium magnetic resonance probe or the purposes of macromole antibacterial.