CN117126398A - Polylysine grafted polymer, preparation method thereof, polymer modified micro-fluidic chip and detection device comprising polymer modified micro-fluidic chip - Google Patents

Abstract

The application provides a lysine graft polymer. The polymer comprises a main chain formed by polymerization of lysine monomers, a side chain formed by grafting lysine, and a side chain containing one or more reactive functional groups for coupling reaction with molecules containing alkoxy units to obtain hydrophilic side chain tail chains. When the lysine graft polymer is used for modifying a microfluidic chip, as the main chain of the graft polymer is a hydrophobic peptide bond and the side chain is a hydrophilic group, the lysine graft polymer can be arranged at the interface of the chip in a regular spiral structure, and the even distribution of hydrophilic units can greatly reduce the defect of the interface of the chip, so that the nonspecific adsorption of nucleic acid, protein and cells on the interface of the chip is further reduced, and the sensitivity and the practicability of the chip in biological detection are improved. The application also provides a preparation method of the lysine graft polymer, a microfluidic chip modified by the lysine graft polymer and a monitoring device comprising the microfluidic chip.

Description

Polylysine grafted polymer and preparation method thereof, polymer-modified microfluidic core Chip and detection device containing the chip

Technical field

The invention belongs to the field of biomedical technology, and in particular relates to a polylysine graft polymer and its modified microfluidic chip and a detection device containing the chip.

Background technique

Microfluidic Chip, also known as Lab-on-a-Chip or biochip, uses microelectromechanical processing technology to shrink a large laboratory system on a glass or plastic substrate. Replicate the entire process of complex biological and chemical reactions and complete experiments quickly and automatically. It is characterized by constructing channels, reaction chambers and other functional components to accommodate fluids at the micron scale, and controlling the movement of trace amounts of fluid in tiny spaces, thereby Build a complete chemistry or biology laboratory.

Microfluidic chips generally include two parts: substrate and structure. The substrate is usually made of glass and silicon wafer materials. The structural part is mostly glass or micron-level fluid channels built from polymer materials such as PDMS, PMMA and SU8, namely microchannels. The properties of the microchannel surface largely determine the functionality and application areas of the microfluidic chip. However, microfluidic chips made of many materials, including glass and polymers, have charged surfaces or are highly hydrophobic, which seriously affects fluid injection, flow, solute adsorption, and related electric fluids. Kinetic effects thus greatly limit the range of analytes and reduce the sensitivity and practicality of microfluidic chips.

In order to solve the above technical problems, it is usually necessary to carry out appropriate molecular modifications on the surface of microfluidic chips to improve chip performance and increase sensitivity. At present, the interface modification method for glass-based microfluidic chips is mainly covalently modified polyethylene glycol. This molecule is believed to be able to strongly bind water molecules, thereby forming a physical or energy barrier, which makes proteins, nucleic acids, platelets, cells, etc. Far away from the matrix surface; in addition, polyethylene glycol molecules have great applications in solution antibacterial, surface antifouling and drug delivery due to their very good biocompatibility. Despite this, polyethylene glycol still has many shortcomings, such as difficulty in functional modification, very slow biodegradation, and uneven thickness of the film formed on the glass surface, which greatly restricts the further improvement of chip performance.

Based on this, new molecular modifications or polyethylene glycol derivatives are developed to modify the chip interface to achieve non-specific "zero" adsorption of biological analytes, which is beneficial to microfluidic technology in biomedicine and diagnostic research. Its application is crucial and is also one of the urgent problems to be solved in the field of interface chemistry.

Contents of the invention

In order to solve the problems of non-specific adsorption at the interface of microfluidic chips in the existing technology, which makes biological analysis and detection have low sensitivity and poor practicality, it is combined with the properties of lysine molecules that are easy to branch to form multi-reactive functional groups, and alkoxy functional groups. It can inhibit the non-specific adsorption of biomolecules. The present invention develops a lysine graft polymer and its modified microfluidic chip and a detection device containing the chip.

In a first aspect, the present invention proposes a lysine graft polymer having a structure represented by formula (I):

Among them, 10≤n≤50, R' is a tail chain group that can be bonded to the chip interface, and R ₁ has the structure shown in any one of formulas (II)-(IV),

Wherein, R ₂ has the structure shown in any one of formulas (V)-(VI),

Where 2≤m≤10. In the structural formula of the present invention Indicates the connection site.

As a specific embodiment of the present invention, in formula (I), 15≤n≤25 is preferred. As n increases, the dispersion of the polymer also increases. Excessive dispersion is not conducive to the modification of the chip interface by the polymer. When 15≤n≤25, the polymer has better modification effect on the chip interface; n in formula (I) is further preferably 15, 18, 20, 22 or 25.

As a specific embodiment of the present invention, when the polymer is combined with the chip interface through hydrophobic interaction, it is preferred that R' is an alkyl carbon chain group; further preferably, R' has any one of formulas (VII) to (VIII) The structure shown is,

Among them, 5≤z≤20; 2≤y≤8.

As a specific embodiment of the present invention, when the polymer is bonded to the chip interface through a covalent bond, it is preferred that the main chain or side chain end of R' contains a siloxy group or a silyl group, and further preferably, the main chain of R' Or the side chain contains an oligoethylene glycol linking chain, and further preferably, R' has a structure shown in any one of formulas (IX)-(X),

Among them, 5≤z≤20.

As a specific embodiment of the present invention, in formula (V), 3≤m≤6 is preferred. For the graft polymer provided in this disclosure, from a synthetic perspective, it can be prepared when 2≤m≤10, but the larger m is, the yield of the corresponding polymer will be significantly reduced due to steric hindrance effect. When m exceeds 10 , almost no product; in terms of its modification effect on the chip surface, the effect of m=2 is close to that of oligoethylene glycol. When 3≤m≤6, its effect is better than that of oligoethylene glycol. Taking all factors into consideration, 3≤m≤6 is preferred, which can not only ensure a higher synthesis yield but also obtain excellent modification performance; m in formula (V) is further preferably 3, 4, 5 or 6.

As a specific embodiment of the present invention, the sugar ring structure in formula VI is preferably an oligosaccharide structure, and further preferably, the oligosaccharide structure is a mannose structure, a dimannose structure or a trimannose structure.

The present invention has no special limitation on the preparation method of the lysine graft polymer, which can be prepared by the lysine-N-carboxylic intracyclic acid anhydride ring-opening polymerization method and the lysine α-amino dehydration condensation method. ; The former can be divided into the ε-amino branch modification method before polymerization and the ε-amino branch modification method after polymerization; correspondingly, the dehydration condensation method also includes two similar schemes. The specific steps can be prepared according to methods well known to those skilled in the art, preferably by referring to the following methods:

(1) ε-amino protection: protect the ε-amino group of lysine-N-carboxylic anhydride within the ring, such as t-Butyloxy carbonyl (Boc) or benzyloxycarbonyl (Cbz) ).

(2) Polymerization reaction: lysine-N-carboxylic intracyclic acid anhydride (molecule 1) after ε-amino protection is ring-opening polymerized under the action of initiator, and then in strong organic acid (such as TFA, p-toluenesulfonic acid) ) and other catalysts to remove the protecting group to obtain α-polylysine (molecule 2);

Among them, the terminal of the initiator is an amino-containing alkyl carbon chain or an ethoxy chain, which may contain an aromatic ring structure and a heteroatom group. When covalently bonded to the chip interface, the end of the main chain or side chain of the initiator must contain a siloxy or silyl group; the end of the initiator includes, but is not limited to, the following structure:

Among them, 5≤z≤20; 2≤y≤8.

Among them, the catalysts are strong organic acids such as trifluoroacetic acid (TFA) and p-toluenesulfonic acid.

(3) Grafting reaction: a condensation reaction occurs between α-polylysine and 2,6-di-tert-butoxycarbonylaminocaproic acid (molecule 3), and in the presence of catalysts such as strong organic acids (such as TFA, p-toluenesulfonic acid) The protecting group is removed under the action of the molecule to obtain molecule 4 with a diamino group at the end of the side chain; molecule 4 undergoes a nucleophilic substitution reaction with pentafluorophenyl tert-butoxycarbonylaminooxyacetate (molecule 5), and the protecting group is removed again to obtain the terminal Molecule 6 containing active amino groups; the amino group at the end of molecule 6 undergoes a substitution reaction with the hydroxyl group at the end of oligoethylene glycol or oligosaccharide molecules to obtain the target product 7.

More preferably, it is prepared according to the following synthetic route:

(1) Under the action of an initiator, lysine-N-carboxylic intracyclic acid anhydride molecule 1 is ring-opened and polymerized, and the protective group is removed under the action of trifluoroacetic acid to obtain α-polylysine, molecule 2.

(2) Molecule 2 and molecule 3 undergo a dehydration condensation reaction, and the protecting group is removed to obtain molecule 4 with a diamino group at the end of the side chain.

(3) Molecule 4 and molecule 5 undergo a nucleophilic substitution reaction, and the protecting group is removed to obtain molecule 6 with an active amino group at the end.

(4) The amino group at the 6-terminal end of the molecule undergoes a substitution reaction with the hydroxyl group at the end of the oligoethylene glycol or oligosaccharide molecule to obtain the target product 7.

The above-mentioned raw materials in the present invention can be homemade or commercially available, and the present invention is not particularly limited thereto.

It can be seen from the above examples of synthetic methods that the lysine grafted polymer disclosed in the present invention is simple to synthesize, and derivatives with different side chains can be obtained by just a few consecutive steps of the same reaction.

In a second aspect, the present invention provides a method for preparing the above-mentioned polylysine graft polymer. The polylysine graft polymer is prepared by method (1) lysine-N-carboxylic intracyclic acid anhydride. Prepared by cyclopolymerization or method (2) dehydration condensation of the amino group at the α-position of lysine; preferably,

The method (1) selects method (1-1) before polymerization ε-amino branch modification method or method (1-2) method (1-2) after polymerization ε-amino branch modification method;

The method (2) selects method (2-1) ε-amino branching modification method before dehydration condensation or method (1-2) ε-amino branching modification method after dehydration condensation.

As a specific embodiment of the present invention, preferably, the preparation method includes the following steps:

(1) ε-amino protection: Use tert-butoxy carbonylation or benzyloxy carbonylation to protect the ε-amino group of lysine-N-carboxylic intracyclic anhydride to obtain the ε-amino-protected lysine- N-carboxylic intracyclic anhydride;

(2) Polymerization reaction: Ring-opening polymerization of lysine-N-carboxylic intracyclic acid anhydride after ε-amino protection is carried out under the action of initiator, and then the protecting group is removed under the action of strong organic acid catalyst to obtain α-polylysine Amino acid; further preferably, the end of the initiator is an amino-containing alkyl carbon chain or an ethoxy chain, and even more preferably, the end of the initiator has any one of the formulas (IX)-(X) The structure shown is,

In formula (IX) and formula (X), 5≤z≤20;

Or the end of the initiator is an alkyl carbon chain, and further preferably, the end of the initiator has a structure shown in any one of formulas (VII-VIII),

In formula (VII) and formula (VIII), 5≤z≤20; 2≤y≤8;

(3) Grafting reaction: α-polylysine undergoes a condensation reaction with 2,6-di-tert-butoxycarbonylaminocaproic acid, and removes the protecting group under the action of a strong organic acid catalyst, and reacts with tert-butoxycarbonylaminocaproic acid Pentafluorophenyl acetate undergoes a nucleophilic substitution reaction, and the protecting group is removed again to obtain an active amino group. The latter amino group undergoes a substitution reaction with the hydroxyl group at the end of the oligoethylene glycol or oligosaccharide molecule to obtain the target product;

Preferably, the strong organic acid catalysts in steps (2) and (3) are independently selected from at least one of trifluoroacetic acid and p-toluenesulfonic acid.

In a third aspect, the present invention provides a microfluidic chip, part or all of its interface is modified by the above-mentioned lysine graft polymer.

As a specific embodiment of the present invention, preferably, the substrate of the microfluidic chip is made of glass or silicon wafer material.

In a fourth aspect, the present invention provides a detection device, including the above-mentioned microfluidic chip.

As a specific embodiment of the present invention, the detection device can be used for isolation of blood free DNA (cell free DNA), immune detection, etc.

The beneficial effects of the present invention are as follows:

The graft polymer provided by the present disclosure includes a main chain formed by polymerization of lysine monomer, and a side chain formed by grafting lysine. The side chain contains one or more reactive functional groups for use with polymers containing alkoxy units. The molecules undergo coupling reactions to form side chain tails containing alkoxy units. This structure has the following advantages:

(1) Since the main chain is a hydrophobic peptide bond and the side chain tail chain is a hydrophilic group, the polymer can be arranged at the chip interface in a regular spiral structure. At the same time, the alkoxy groups in the side chain tail chain Clusters can also be evenly and densely distributed on the chip interface, thereby greatly reducing defects at the chip interface and reducing non-specific adsorption of nucleic acids, proteins and cells on the chip interface.

(2) Since the lysine side chain has a branched structure, multiple functional side chain tail chains can be derived from it. Therefore, numerous alkoxy tail chains are evenly arranged around the helical structure, forming a complete structure on the substrate surface. A physical barrier to prevent non-specific adsorption of biomolecules on the substrate surface.

In summary, this polymer can be used to modify the interface of microfluidic chips, which can significantly reduce its non-specific adsorption of nucleic acids, proteins and cells, and help improve the sensitivity and practicality of microfluidic chips in biological detection.

Description of the drawings

Figure 1 is a schematic structural diagram of the surface of a P(Lys-EG ₁ )-modified glass chip prepared in Example 4 of the present invention;

Figure 2 is a schematic structural diagram of the glass-based chip channel in the detection device provided in Embodiment 5;

1. Microfluidic channel, 11. Inlet flow channel, 12. Reaction flow channel, 13. Sample outlet flow channel,

2. Color development area, 21. Sample capture color development area, 22. Sample capture color development area.

Detailed ways

The present invention will be further described below with reference to specific examples, but this does not constitute any limitation on the present invention.

The specific raw materials used in each embodiment of the present invention can be homemade or commercially available, and the present invention is not particularly limited thereto.

The lysine grafted polymer provided by the invention is preferably prepared by referring to the following synthetic route 1:

(1) Under the action of an initiator, lysine-N-carboxylic intracyclic acid anhydride molecule 1 is ring-opened and polymerized, and the protective group is removed under the action of trifluoroacetic acid to obtain α-polylysine, molecule 2.

(2) Molecule 2 and molecule 3 undergo a dehydration condensation reaction, and the protecting group is removed to obtain molecule 4 with a diamino group at the end of the side chain.

(3) Molecule 4 and molecule 5 undergo a nucleophilic substitution reaction, and the protecting group is removed to obtain molecule 6 with an active amino group at the end.

(4) The amino group at the 6-terminal end of the molecule undergoes a substitution reaction with the hydroxyl group at the end of the oligoethylene glycol or oligosaccharide molecule to obtain the target product 7.

(1) Preparation of lysine graft polymer

Example 1

Synthesis of branched polymer P (Lys-EG ₁ ) containing one oligoethylene glycol molecule in the lysine side chain

(1) Referring to synthetic route 1, molecule 2 is obtained by ring-opening polymerization of molecule 1. In anhydrous tetrahydrofuran, anhydrous N,N-dimethylformamide or N-methylpyrrolidone solvent (1.0 mL), tert-butoxycarbonyl (Boc) protected lysine-N-carboxylic intracyclic anhydride (0.15 mmol) under the action of initiator dodecylamine (0.0075mmol), stirred at room temperature (27°C) overnight (15 hours), then ring-opening polymerized, and then in 2mL trifluoroacetic acid (TFA) and dichloromethane mixed solvent (v :v=1:1) at room temperature (27°C) for 0.5 hours to remove the Boc protecting group to obtain α-polylysine represented by molecule 2.

(2) tert-butoxycarbonylaminooxyacetic acid (15.5mmol) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) (18.6mmol) in dichloromethane ( 50 mL) solution was cooled to zero on ice, then a solution of pentafluorophenol (17.1 mmol) in dichloromethane (5 mL) was added, then gradually returned to room temperature (27°C) and stirred for 5 hours to obtain oxycarbonylaminooxyacetic acid pentafluoro Phenyl-tert-butyl ester, molecule 5.

(3) The molecule of formula 6-1 is prepared from the reaction of molecules 2 and 5 (similar in structure to molecule 6 in synthesis route 1, but with different degrees of branching)

Dissolve molecule 2 (1.30mmol) and N,N-diisopropylethylamine (DIPEA) (3.88mmol) in 1mL DMSO, then add molecule 5 (25.0mmol); the resulting reaction mixture is stirred at room temperature for 1 hour, and 2mL is added After removing methanol, precipitate with diethyl ether. Then add 2 mL of trifluoroacetic acid (TFA) to the precipitated solid, stir at room temperature for 0.5 hours, evaporate excess TFA under reduced pressure, add 2 mL of methanol to the residue, and precipitate with diethyl ether to obtain the molecule of formula 6-1.

(4) Dissolve the molecule with the structure of formula 6-1, oligoethylene glycol and aniline in HAc/NaAc buffer (pH=4.2); react at 37°C overnight; after dialyzing with distilled water, the resulting solution is freeze-dried to obtain Branched polymer P(Lys-EG ₁ ). Among them, the molar ratio of the molecule of formula 6-1, oligoethylene glycol and aniline is 0.80:1.0:0.50.

Example 2

Synthesis of branched polymer P (Lys-EG ₂ ) containing two oligoethylene glycol molecules in the lysine side chain

The only difference between the synthesis of branched polymer P(Lys-EG ₂ ) and the synthesis of P(Lys-EG ₁ ) in Example 1 lies in the preparation of molecule 4, and the remaining steps are the same. Molecule 4 is prepared by putting molecule 2 and molecule 3 into a mixed solvent of methylene chloride and hydroxyacenetriazole, and then condensing them catalytically by EDC to obtain molecule 4. Specifically, it includes the following steps:

Dissolve Boc-Lys(Boc)-OH (molecule 3, 20.1mmol), EDC (23.0mmol), and hydroxycenetriazole (23.0mmol) in dichloromethane (50mL), and cool to zero on ice; then N,N-diisopropylethylamine (26.0 mmol) and molecule 2 (1.30 mmol) were slowly added to it in sequence, and then returned to room temperature (27°C) and reacted overnight (15 hours). After the reaction is completed, wash it once with 2M (mol/L) hydrochloric acid, and then separate it with silica gel column chromatography.

The final structural formula of the branched polymer P(Lys-EG ₂ ) is as follows:

Example 3

Synthesis of branched polymer P (Lys-EG ₄ ) containing four oligoethylene glycol molecules in the lysine side chain

The only difference in the synthesis of branched polymer P (Lys-EG ₄ ) and branched polymer P (Lys-EG ₂ ) in Example 2 is that molecule 4-3 is further prepared on the basis of molecule 4 (similar to synthetic route 1 Medium molecule 4 has a similar structure but different degrees of branching), and the rest of the methods are the same.

Preparation of molecule 4-3: from molecule 4 (1.30mmol) and molecule 3 (Boc-Lys(Boc)-OH, 38.0mmol) in a mixed solvent of dichloromethane (50mL) and hydroxybenzotriazole (23.0mmol) In , molecule 4-3 was obtained by catalytic condensation of EDC (23.0 mmol); the specific experimental steps were the same as the preparation of molecule 4 in Example 2.

The final structural formula of the branched polymer P(Lys-EG ₄ ) is as follows:

(2) Preparation and performance of microfluidic chip modified with lysine graft polymer

Example 4

P(Lys-EG ₁ ) modified glass-based surface and its adsorption properties for proteins and nucleic acids

1. The silicon oxide on the chip surface is converted into silicon hydroxyl groups.

Put the glass chip with silicon oxide on the surface into the piranha solution (piranha solution) and soak it for 10 hours at a temperature of 85°C-90°C; the piranha solution is composed of 98wt% concentrated sulfuric acid and 30wt% hydrogen peroxide. Wherein, the volume ratio of the concentrated sulfuric acid and the 30% hydrogen peroxide is 1:3.

Then, rinse the chip twice with deionized water. The rinsed chip was ultrasonically cleaned in deionized water and then dried with nitrogen for later use.

2. Hydrophobic modification of the glass chip surface.

Place the glass chip with silicone hydroxyl groups on the surface into a toluene solution of 0.5% (v/v) dedecyltrimethoxysilane, and soak it in a sealed container at 35° C. for 30 hours. After the reaction is completed, pour away the reaction solution, rinse the chip twice with deionized water, and then ultrasonically clean the chip with deionized water for 5 minutes to remove impurities contaminated on the chip; then use nitrogen to dry the chip.

3. P(Lys-EG ₁ ) modified glass chip

A solution with a concentration of 5.0 mg/mL was prepared using branched polylysine P (Lys-EG ₁ ) prepared in Example 1 and PBS buffer (pH 7.4). The cleaned glass chip was then immersed in the above polymer solution and incubated on a shaker at room temperature for 24 hours. Finally, the coated glass-based chip was rinsed thoroughly with ultrapure water and dried with a nitrogen stream.

The steps for modifying the glass chip with branched polylysine P (Lys-EG ₂ ) prepared in Example 2 and branched polylysine P (Lys-EG ₄ ) prepared in Example 3 are the same as the above method.

The preparation method of PEG-coated glass chips is the same as the above steps, and the PEG used is cetyl polyoxyethylene ether.

4. Protein and nucleic acid adsorption experiments

The glass chips without polymer coating (Bare Glass) and those coated with grafted polymers (P(Lys-EG ₁ ), P(Lys-EG ₂ ), P(Lys-EG ₄ )) were rinsed with PBS buffer respectively. layer of glass chips and glass chips with PEG coating. At 25°C, flow the newly prepared protein solution (BSA, 1.0mg/mL) or oligonucleotide solution (21nt-dsDNA, 1.5mg/mL) through the chip at a flow rate of 50μL/min for 15 minutes respectively, and then use Rinse the chip surface with PBS buffer for 15 minutes. The amount of proteins and oligonucleotides adsorbed on the glass surface was determined by measuring the fluorescent groups modified on the above molecules. The measurement results are shown in Table 1.

Table 1

21nt dsDNA BSA Bare Glass 100% 100% P(Lys-EG ₁ ) 3.2% 4.0% P(Lys-EG ₂ ) 3.4% 3.7% P(Lys-E ₄ ) 2.7% 2.9% PEG 10.2% 13.0%

As can be seen from Table 1, compared with PEG, the lysine grafted polymer of the present disclosure can significantly reduce its non-specific adsorption of oligonucleotides and proteins after coating the glass interface, and from P(Lys-EG ₁ ) to P(Lys-EG ₂ ), and then to P(Lys-EG ₄ ), as the number of oligoethylene glycols at the end of the branched side chain increases, the non-specific "zero" adsorption effect becomes more obvious.

(3) Detection device

Example 5

This embodiment provides a detection device including the glass chip with P(Lys-EG ₁ ) coating prepared in Example 4 to achieve non-specific "zero" adsorption of the analyte to be analyzed and improve the signal-to-noise ratio of the detection site. The detection device is used for biological detection. The structure of its glass-based chip channel is shown in Figure 2. The microfluidic channel 1 includes a sample flow channel 11, a reaction flow channel 12 and a sample outlet flow channel 13; the color development area 2 includes A sample capture color developing area 21 is provided between the inlet flow channel 11 and the reaction flow channel 12 , and a sample capture color development area 22 is provided between the reaction flow channel 12 and the sample outlet flow channel 13 .

In order to avoid non-specific adsorption of the sample on the glass base surface during the flow process, thereby reducing the sensitivity of the experiment, this embodiment was performed on the inlet flow channel 11, the reaction flow channel 12 and the sample outlet flow channel 13 in the same manner as in Example 4. P(Lys-EG ₁ ) coating. The reaction that occurs in the sample capture and color development areas 21 and 22 can be a hybridization capture reaction of an oligonucleotide single chain or an antigen-antibody specific recognition reaction, which can be designed according to specific experimental details without excessive restrictions here.

Of course, in other embodiments, all or part of the color developing area 2 can be coated at the same time, leaving only the area to be reacted.

To sum up, the graft polymer provided by the present disclosure includes a main chain formed by the polymerization of lysine monomer, and a side chain formed by grafting lysine. The side chain contains one or more reactive functional groups for and containing alkane. Molecules with oxygen units undergo coupling reactions to form side chain tails containing alkoxy units. The polymer is used to modify the interface of microfluidic chips, which can significantly reduce non-specific adsorption of nucleic acids, proteins and cells, and helps improve the sensitivity and practicality of microfluidic chips in biological detection. The structure of this polymer offers the following advantages:

(1) Since the main chain is a hydrophobic peptide bond and the side chain tail chain is a hydrophilic group, the polymer can be arranged at the chip interface in a regular spiral structure. At the same time, the alkoxy groups in the side chain tail chain Clusters can also be evenly and densely distributed on the chip interface, thereby greatly reducing defects at the chip interface and reducing non-specific adsorption of nucleic acids, proteins and cells on the chip interface.

(2) Since the lysine side chain has a branched structure, multiple functional side chain tail chains can be derived from it. Therefore, numerous alkoxy tail chains are evenly arranged around the helical structure, forming a complete structure on the substrate surface. A physical barrier to prevent non-specific adsorption of biomolecules on the substrate surface.

Any reference in this invention to any numerical value which separates any minimum value from any maximum value by only two units, includes all values increments of one unit from the lowest value to the highest value. For example, if it is stated that the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is 50-90, in this specification it means that 51-89, 52-88...and 69 are specifically enumerated. Values such as -71 and 70-71. For non-integer values, units of 0.1, 0.01, 0.001 or 0.0001 may be appropriately considered. These are just some specific examples. In this application, in a similar manner, all possible combinations of numerical values between the lowest value and the highest value listed are considered to have been disclosed.

It should be noted that the above-described embodiments are only used to explain the present invention and do not constitute any limitation on the present invention. The invention has been described with reference to exemplary embodiments, but it is to be understood that the words used therein are descriptive and explanatory rather than restrictive. The invention may be modified as specified within the scope of the claims of the invention and may be modified without departing from the scope and spirit of the invention. Although the invention described therein relates to specific methods, materials and embodiments, it is not intended that the invention be limited to the specific examples disclosed therein, but rather the invention extends to all other methods and applications having the same function.

Claims (10)

1. A polylysine graft polymer, characterized in that it has a structure represented by formula (I): Among them, 10≤n≤50, R' is a tail chain group, and R ₁ has the structure shown in any one of formulas (II)-(IV), Wherein, R ₂ has the structure shown in any one of formulas (V)-(VI), Where 2≤m≤10. 2. The polymer according to claim 1, characterized in that 15≤n≤25, preferably 15, 18, 20, 22 or 25. 3. The polymer according to claim 1 or 2, characterized in that R' is an alkyl carbon chain group, preferably, R' has a structure shown in any one of formulas (VII)-(VIII), Among them, 5≤z≤20; 2≤y≤8. 4. The polymer according to claim 1 or 2, characterized in that the main chain or side chain terminal of R′ contains a siloxy group or a silyl group. Preferably, the main chain or side chain of R′ contains an oligoethyl group. Diol connecting chain; more preferably, R' has a structure shown in any one of formulas (IX)-(X), Among them, 5≤z≤20. 5. The polymer according to any one of claims 1 to 4, characterized in that 3≤m≤6, preferably 3, 4, 5 or 6. 6. The polymer according to any one of claims 1 to 5, characterized in that the sugar ring structure in Formula VI is an oligosaccharide structure. Preferably, the oligosaccharide structure is a mannose structure, a dimannose structure or a trimannose structure. Mannose structure. 7. A method for preparing the polylysine graft polymer according to any one of claims 1 to 6, characterized in that the polylysine graft polymer is prepared by method (1) lysine -N-carboxylic intracyclic acid anhydride is prepared by ring-opening polymerization or method (2) lysine α-amino dehydration condensation method; preferably, The method (1) selects method (1-1) before polymerization ε-amino branch modification method or method (1-2) method (1-2) after polymerization ε-amino branch modification method; The method (2) selects method (2-1) ε-amino branching modification method before dehydration condensation or method (1-2) ε-amino branching modification method after dehydration condensation. 8. The preparation method according to claim 7, characterized in that the preparation method includes the following steps: (1) ε-amino protection: Use tert-butoxy carbonylation or benzyloxy carbonylation to protect the ε-amino group of lysine-N-carboxylic intracyclic anhydride to obtain the ε-amino-protected lysine- N-carboxylic intracyclic anhydride; (2) Polymerization reaction: Ring-opening polymerization of lysine-N-carboxylic intracyclic acid anhydride after ε-amino protection is carried out under the action of initiator, and then the protecting group is removed under the action of strong organic acid catalyst to obtain α-polylysine Acid; Preferably, the end of the initiator is an amino-containing alkyl carbon chain or an ethoxy chain, and further preferably, the end of the initiator has a structure shown in any one of formulas (IX) to (X), In formula (IX) and formula (X), 5≤z≤20; Or the end of the initiator is an alkyl carbon chain, and further preferably, the end of the initiator has a structure shown in any one of formulas (VII-VIII), In formula (VII) and formula (VIII), 5≤z≤20; 2≤y≤8; (3) Grafting reaction: α-polylysine undergoes a condensation reaction with 2,6-di-tert-butoxycarbonylaminocaproic acid, and removes the protecting group under the action of a strong organic acid catalyst, and reacts with tert-butoxycarbonylaminocaproic acid Pentafluorophenyl acetate undergoes a nucleophilic substitution reaction, and the protecting group is removed again to obtain an active amino group. The latter amino group undergoes a substitution reaction with the hydroxyl group at the end of the oligoethylene glycol or oligosaccharide molecule to obtain the target product; Preferably, the strong organic acid catalysts in steps (2) and (3) are independently selected from at least one of trifluoroacetic acid and p-toluenesulfonic acid. 9. A microfluidic chip, characterized in that part or all of its interface is modified by the polylysine graft polymer according to any one of claims 1-6, or is modified by any one of claims 7-8 The polylysine graft polymer obtained by the preparation method is modified. Preferably, the substrate of the microfluidic chip is made of glass or silicon wafer material. 10. A detection device, characterized by comprising the microfluidic chip according to claim 9.