Polyamino acid hydrogel, hydrogel catheter and preparation method thereof

Abstract

The present invention provides a polyamino acid hydrogel and a preparation method thereof, as well as a hydrogel catheter and a preparation method thereof. The present invention prepares chiral lysine N-carboxyl anhydride and L-glutamic acid N-carboxyl anhydride respectively, and then uses them as raw materials, initiates with double-terminal amino polyethylene glycol NH2-PEG-NH2, and prepares double-terminal polylysine polymers shown in formula (I'-1) / formula (I'-2) and double-terminal polyglutamic acid polymers of formula (II'), respectively. Afterwards, double-terminal polylysine polymer solutions and double-terminal polyglutamic acid polymer solutions are prepared respectively, and the two solutions are mixed in a catheter consisting of an electrospinning membrane, and quickly gelled to form a hydrogel catheter. The above-mentioned hydrogel is filled inside, which has a supporting effect on the catheter, avoids the problem that the hollow catheter is easy to collapse, and at the same time simulates the natural nerve cell extracellular matrix by the hydrogel itself and its degradation products, thereby achieving a better peripheral nerve defect repair effect.

Description

Technical Field

[0001] The present invention relates to the field of biomaterials, and in particular to a polyamino acid hydrogel, a hydrogel catheter and a preparation method thereof. Background Art

[0002] Peripheral nerve defect repair is a complex process involving multiple cells. For defects that cannot be sutured directly, tissue-engineered nerve conduits are often used to bridge the gap, providing structural support and biochemical guidance for nerve regeneration. A variety of biomaterials have been developed for peripheral nerve repair, such as electrospun membranes, hydrogel scaffolds, nanoparticles, or nanofibers. While these have achieved some success, most are hollow conduits, which have limited guidance for regenerating nerves and struggle to adapt to the demands and patterns of the regenerative microenvironment during dynamic changes.

[0003] Currently, most existing nerve conduits are hollow. In theory, improvements in the design, synthesis, and preparation of conduit materials, as well as physical and chemical modifications to the conduit's inner wall, could potentially promote peripheral nerve regeneration. However, in practice, hollow conduits lack sufficient support and are prone to collapse upon implantation. Furthermore, they fail to mimic the effects of the natural extracellular matrix (ECM) of neural cells. Summary of the Invention

[0004] In light of this, the present invention provides a polyamino acid hydrogel, a hydrogel catheter, and a method for preparing the same. The polyamino acid hydrogel and hydrogel catheter provided by the present invention can mimic natural nerve ECM to repair peripheral nerve defects. Furthermore, their superior supportive strength prevents the collapse of hollow catheters.

[0005] The present invention provides a method for preparing a polyamino acid hydrogel, comprising the following steps:

[0006] (A) Preparation of chiral lysine-N-carboxylic anhydride:

[0007] N(ε)-benzyloxycarbonyl-lysine reacts with triphosgene to form lysine-N-carboxylic anhydride;

[0008] in,

[0009] The N(ε)-benzyloxycarbonyl-lysine is N(ε)-benzyloxycarbonyl-L-lysine or N(ε)-benzyloxycarbonyl-D-lysine;

[0010] The obtained lysine-N-carboxyl internal anhydride is L-lysine-N-carboxyl internal anhydride represented by formula (I-1) or D-lysine-N-carboxyl internal anhydride represented by formula (I-2);

[0011] (B) Preparation of L-glutamic acid-N-carboxylic anhydride:

[0012] γ-Benzyl-L-glutamate reacts with triphosgene to form L-glutamic acid-N-carboxylic anhydride represented by formula (II);

[0013] (C) Preparation of double-terminated polylysine polymers:

[0014] reacting the lysine-N-carboxylic anhydride with double-terminated amino polyethylene glycol NH2-PEG-NH2 to form a double-terminated polylysine polymer;

[0015] in,

[0016] The lysine-N-carboxyl internal anhydride is L-lysine-N-carboxyl internal anhydride represented by formula (I-1) or D-lysine-N-carboxyl internal anhydride represented by formula (I-2);

[0017] The obtained double-terminal polylysine polymer is a double-terminal polylysine polymer PLL-PEG-PLL represented by formula (I'-1) or a double-terminal polylysine polymer PDL-PEG-PDL represented by formula (I'-2);

[0018] (D) Preparation of double-terminated polyglutamic acid polymers:

[0019] The L-glutamic acid-N-carboxyl anhydride represented by formula (II) is reacted with double-terminal amino polyethylene glycol NH2-PEG-NH2 to form a double-terminal polyglutamic acid polymer PGlu-PEG-PGlu represented by formula (II');

[0020] (E) Preparation of hydrogel:

[0021] E1: dissolving the double-terminated polylysine polymer obtained in step (C) in water, adjusting the pH value, dialyzing, drying, and then mixing with a solvent to prepare a double-terminated polylysine polymer solution;

[0022] E2: dissolving the double-terminated polyglutamic acid polymer obtained in step (D) in water, adjusting the pH value, dialyzing, drying, and then mixing with a solvent to prepare a double-terminated polyglutamic acid polymer solution;

[0023] E3: mixing the double-terminal poly-lysine polymer solution obtained in step E1 with the double-terminal poly-glutamic acid polymer solution obtained in step E2 to obtain an ionically cross-linked hydrogel;

[0024] , ;

[0025] Formula (I-1) Formula (I-2);

[0026]

[0027] Formula (II);

[0028] , ;

[0029] Formula (I'-1) Formula (I'-2);

[0030]

[0031] Formula (II');

[0032] Among them, the degree of polymerization x≥30, m1≥35, m2≥35;

[0033] There is no particular restriction on the order of the steps in each step.

[0034] Preferably, in step (A), the reaction temperature is 55-58°C;

[0035] In step (B), the reaction temperature is 55-58°C.

[0036] Preferably, in step (C):

[0037] The reaction comprises sequentially performing a polymerization reaction and a deprotection reaction;

[0038] The polymerization reaction temperature is 20-26°C;

[0039] The deprotection reaction is carried out in the presence of a hydrogen bromide solution; the hydrogen bromide solution is a hydrogen bromide acetic acid solution;

[0040] The temperature of the deprotection reaction is 20-26°C.

[0041] Preferably, in step (D):

[0042] The reaction comprises sequentially performing a polymerization reaction and a deprotection reaction;

[0043] The polymerization reaction temperature is 20-26°C;

[0044] The deprotection reaction is carried out in the presence of a hydrogen bromide solution; the hydrogen bromide solution is a hydrogen bromide acetic acid solution;

[0045] The temperature of the deprotection reaction is 20-26°C.

[0046] Preferably, the degree of polymerization x is 30-95, m1 is 35-85, m2 is 35-85, and m1=m2.

[0047] Preferably, in step E1:

[0048] Dissolving the double-terminated polylysine polymer obtained in step (C) in water to obtain a solution with a concentration of 5% to 20%;

[0049] The pH value is adjusted to 7.0-7.8;

[0050] In step E2:

[0051] Dissolving the double-terminated polyglutamic acid polymer obtained in step (D) in water to obtain a solution with a concentration of 5% to 20%;

[0052] The pH value is adjusted to 7.0-7.8;

[0053] In step E3:

[0054] When the double-terminal polylysine polymer solution obtained in step E1 is mixed with the double-terminal polyglutamic acid polymer solution obtained in step E2, the molar ratio of amino groups in the double-terminal polylysine polymer to carboxyl groups in the double-terminal polyglutamic acid polymer is controlled to be 1:(0.8-1.2).

[0055] The present invention also provides a polyamino acid hydrogel prepared by the preparation method described in the above technical solution.

[0056] The present invention also provides a method for preparing a hydrogel catheter, comprising the following steps:

[0057] S1, dissolving a polymer in a solvent to obtain a spinning solution; then, performing electrospinning to obtain a polymer film;

[0058] S2, forming the polymer film into a tube to obtain a catheter;

[0059] S3, mixing the double-ended poly-lysine polymer solution and the double-ended poly-glutamic acid polymer solution into a gel in the catheter to obtain a hydrogel catheter;

[0060] The double-terminated poly-lysine polymer solution is prepared by step E1 of the preparation method described in the above technical solution, and the double-terminated poly-glutamic acid polymer solution is prepared by step E2 of the preparation method described in the above technical solution.

[0061] Preferably, in step S2, the electrospun membrane is formed into a tube by winding it into a tube, comprising: cutting the polymer film obtained in step S1 into a rectangular shape, rolling the polymer film into a tube with a cylindrical mold as an axis, and then fixing the edges to obtain a catheter;

[0062] When the polymer film is cut into a rectangle, the parallel-oriented side is the length side and the vertical-oriented side is the width side; the parallel-oriented side corresponds to the catheter length and the vertical-oriented side is larger than the mold circumference; the fixing method is suturing.

[0063] The present invention also provides a hydrogel catheter prepared by the preparation method described in the above technical solution.

[0064] The preparation method of the polyamino acid hydrogel provided by the present invention comprises steps (A) to (E). Specifically, chiral lysine-N-carboxyl anhydride and L-glutamic acid-N-carboxyl anhydride are prepared respectively, and then used as raw materials respectively to initiate with double-terminal amino polyethylene glycol NH2-PEG-NH2 to prepare double-terminal polylysine polymers represented by formula (I'-1) / formula (I'-2) and double-terminal polyglutamic acid polymers represented by formula (II'), respectively. Subsequently, double-terminal polylysine polymer solutions and double-terminal polyglutamic acid polymer solutions are prepared respectively, and the two solutions are mixed. The two solutions with opposite charges quickly gel under the action of positive and negative charges to form a uniformly mixed ion-crosslinked hydrogel. The hydrogel catheter provided by the present invention is made based on the above-mentioned chiral ion-crosslinked polyamino acid hydrogel. It is a nerve catheter with a polyamino acid hydrogel interior and an electrospun membrane exterior. The nerve catheter is composed of an oriented polymer electrospun membrane exterior and is filled with a biocompatible, biodegradable chiral polyamino acid hydrogel interior, which has a supporting effect on the catheter and avoids the problem of easy collapse of the hollow catheter. The hydrogel itself and its degradation products simulate the functions of the natural nerve extracellular matrix (ECM) in nourishing cells, contact guidance, and regulating the immune microenvironment, thereby achieving better peripheral nerve defect repair effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0066] Figure 1 Schematic diagram of winding a spinning membrane into a tube according to the present invention;

[0067] Figure 2 is a hydrogen nuclear magnetic resonance spectrum of the double-terminated polylysine polymer represented by formula (I'-1) obtained in step (C) of Example 1 of the present invention;

[0068] Figure 3 is a hydrogen nuclear magnetic resonance spectrum of the double-terminated polylysine polymer represented by formula (I'-2) obtained in step (C) of Example 1 of the present invention;

[0069] Figure 4 is a hydrogen nuclear magnetic resonance spectrum of the double-terminated polyglutamic acid polymer obtained in step (D) of Example 1 of the present invention;

[0070] Figure 5 Circular dichroism spectra of three polyamino acids in Example 1 of the present invention;

[0071] Figure 6This is a rheological test diagram of hydrogels of different concentrations in Example 1 of the present invention; wherein, Figure 6 A is the rheological test graph of PLL+PGlu hydrogel with different concentrations. Figure 6 B is the rheological test graph of PDL+PGlu hydrogel with different concentrations;

[0072] Figure 7 This is a cryo-scanning electron micrograph of the 3 wt% hydrogel in Example 1 of the present invention; wherein, Figure 7 A is the SEM image of PLL+PGlu hydrogel, Figure 7 B is the SEM image of PDL+PGlu hydrogel;

[0073] Figure 8 This is a flow cytometry effect diagram of the hydrogel in Example 1 of the present invention regulating the phenotype of macrophages (RAW 264.7); wherein, Figure 8 A is a quantitative analysis of the proportion of M1 phenotype after macrophages were co-cultured with different materials. Figure 8 B is a quantitative analysis of the proportion of M2 phenotype. Figure 8 C is the analysis diagram of the relative content ratio of M2 and M1;

[0074] Figure 9 is a SEM image of the oriented PLGA film obtained in step S1 of Example 2 of the present invention;

[0075] Figure 10 : is a stress-strain curve of the oriented PLGA film obtained in step S1 of Example 2 of the present invention; wherein Radial is the parallel orientation direction and Tangential is the perpendicular orientation direction;

[0076] Figure 11 This is the appearance diagram of the product in Example 2 of the present invention; wherein, Figure 11 A is the main view of the catheter obtained in step S1, Figure 11 B is a side view of the catheter obtained in step S1, Figure 11 C is a side view of the hydrogel catheter obtained in step S3;

[0077] Figure 12 This is a graph showing the gait analysis of the rat's hind limbs during the in vivo nerve repair effect of the polyamino acid hydrogel catheter in Example 2 of the present invention; wherein, Figure 12 A is the footprint diagram of the autologous transplantation group; Figure 12 B is the footprint diagram of the PLGA empty catheter group; Figure 12 C is the footprint of the internally filled PLL+PGlu hydrogel group; Figure 12 D is the footprint of the internally filled PDL+PGlu hydrogel group;

[0078] Figure 13This is a TEM image of the regenerated nerve tissue in the in vivo nerve repair effect of the polyamino acid hydrogel catheter in Example 2 of the present invention; wherein, Figure 13 A1, A2, and A3 are TEM images of the autologous transplantation group at 2000x, 6000x, and 25000x magnifications, respectively; Figure 13 Figures B1, B2, and B3 are TEM images of the PLGA empty catheter group at 2000x, 6000x, and 25000x magnifications, respectively; Figure 13 C1, C2, and C3 are TEM images of the internally filled PLL+PGlu hydrogel group at 2000x, 6000x, and 25000x magnifications, respectively; Figure 13 D1, D2, and D3 are TEM images of the internally filled PDL+PGlu hydrogel group at 2000x, 6000x, and 25000x magnifications, respectively. DETAILED DESCRIPTION

[0079] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0080] In this article, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0081] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0082] As used herein, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Furthermore, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0083] In this document, when referring to a range, if the unit is followed only by the right endpoint, it means that the units of the left and right endpoints are the same. For example, 1400~2000rpm means that the units of the left endpoint "1400" and the right endpoint "2000" are both rpm.

[0084] The present invention provides a method for preparing a polyamino acid hydrogel, comprising the following steps:

[0085] (A) Preparation of chiral lysine-N-carboxylic anhydride:

[0086] N(ε)-benzyloxycarbonyl-lysine reacts with triphosgene to form lysine-N-carboxylic anhydride;

[0087] in,

[0088] The N(ε)-benzyloxycarbonyl-lysine is N(ε)-benzyloxycarbonyl-L-lysine or N(ε)-benzyloxycarbonyl-D-lysine;

[0089] The obtained lysine-N-carboxyl internal anhydride is L-lysine-N-carboxyl internal anhydride represented by formula (I-1) or D-lysine-N-carboxyl internal anhydride represented by formula (I-2);

[0090] (B) Preparation of L-glutamic acid-N-carboxylic anhydride:

[0091] γ-Benzyl-L-glutamate reacts with triphosgene to form L-glutamic acid-N-carboxylic anhydride represented by formula (II);

[0092] (C) Preparation of double-terminated polylysine polymers:

[0093] reacting the lysine-N-carboxylic anhydride with double-terminated amino polyethylene glycol NH2-PEG-NH2 to form a double-terminated polylysine polymer;

[0094] in,

[0095] The lysine-N-carboxyl internal anhydride is L-lysine-N-carboxyl internal anhydride represented by formula (I-1) or D-lysine-N-carboxyl internal anhydride represented by formula (I-2);

[0096] The obtained double-terminal polylysine polymer is a double-terminal polylysine polymer PLL-PEG-PLL represented by formula (I'-1) or a double-terminal polylysine polymer PDL-PEG-PDL represented by formula (I'-2);

[0097] (D) Preparation of double-terminated polyglutamic acid polymers:

[0098] The L-glutamic acid-N-carboxyl anhydride represented by formula (II) is reacted with double-terminal amino polyethylene glycol NH2-PEG-NH2 to form a double-terminal polyglutamic acid polymer PGlu-PEG-PGlu represented by formula (II');

[0099] (E) Preparation of hydrogel:

[0100] E1: dissolving the double-terminated polylysine polymer obtained in step (C) in water, adjusting the pH value, dialyzing, drying, and then mixing with a solvent to prepare a double-terminated polylysine polymer solution;

[0101] E2: dissolving the double-terminated polyglutamic acid polymer obtained in step (D) in water, adjusting the pH value, dialyzing, drying, and then mixing with a solvent to prepare a double-terminated polyglutamic acid polymer solution;

[0102] E3: mixing the double-terminal poly-lysine polymer solution obtained in step E1 with the double-terminal poly-glutamic acid polymer solution obtained in step E2 to obtain an ionically cross-linked hydrogel;

[0103] , ;

[0104] Formula (I-1) Formula (I-2);

[0105]

[0106] Formula (II);

[0107] , ;

[0108] Formula (I'-1) Formula (I'-2);

[0109]

[0110] Formula (II');

[0111] Among them, the degree of polymerization x≥30, m1≥35, m2≥35;

[0112] There is no particular restriction on the order of the steps in each step.

[0113] The preparation method of the polyamino acid hydrogel provided by the present invention comprises steps (A) to (E). Specifically, chiral lysine-N-carboxyl anhydride and L-glutamic acid-N-carboxyl anhydride are prepared respectively, and then used as raw materials respectively to initiate with double-terminal amino polyethylene glycol NH2-PEG-NH2 to prepare double-terminal polylysine polymers represented by formula (I'-1) / formula (I'-2) and double-terminal polyglutamic acid polymers represented by formula (II'), respectively. Subsequently, double-terminal polylysine polymer solutions and double-terminal polyglutamic acid polymer solutions are prepared respectively, and the two solutions are mixed. The two solutions with opposite charges quickly gel under the action of positive and negative charges to form a uniformly mixed ion-crosslinked hydrogel.

[0114] In the present invention, steps (A) to (E) that are not sequentially related are not subject to specific order restrictions. "Steps that are not sequentially related" refer to steps that do not necessarily have a sequential relationship. For example, in the case of steps (A) and (C), step (C) uses the product obtained in step (A) as a raw material. Therefore, step (A) must be performed before step (C), indicating a sequential relationship. In this case, they must be performed in a specific order. For example, steps (A) and (B), step (A) and (D), and step E1 and step E2 are not sequentially related, and therefore, their order is not specifically restricted. The same applies to the other steps, and they will not be listed one by one.

[0115] About step (A) :

[0116] (A) Preparation of chiral lysine-N-carboxylic anhydride: N(ε)-benzyloxycarbonyl-lysine reacts with triphosgene to form lysine-N-carboxylic anhydride.

[0117] In the present invention, the N(ε)-benzyloxycarbonyl-lysine is N(ε)-benzyloxycarbonyl-L-lysine (ZLL) or N(ε)-benzyloxycarbonyl-D-lysine (ZDL), and the corresponding lysine-N-carboxyanhydrides obtained are L-lysine-N-carboxyanhydrides (L-Lys-N-carboxyanhydrides, abbreviated as L-Lys NCA) shown in formula (I-1) or D-lysine-N-carboxyanhydrides (D-Lys-N-carboxyanhydrides, abbreviated as D-Lys NCA) shown in formula (I-2). That is, step (A) comprises: N(ε)-benzyloxycarbonyl-L-lysine + triphosgene → L-lysine-N-carboxylic anhydride represented by formula (I-1), or N(ε)-benzyloxycarbonyl-D-lysine + triphosgene → D-lysine-N-carboxylic anhydride represented by formula (I-2). The reaction schemes of the above two reactions are as follows:

[0118]

[0119]

[0120] In the present invention, the sources of the raw materials N(ε)-benzyloxycarbonyl-lysine (ZLL, ZDL) and triphosgene (BTC) are not particularly limited and can be commercially available products or prepared according to methods known in the art. In the present invention, the molar ratio of N(ε)-benzyloxycarbonyl-lysine to triphosgene is preferably (1-2.5):1, specifically 1:1, 1.5:1, 2:1, 2.5:1, and more preferably 2:1.

[0121] In the present invention, the reaction is preferably carried out in a protective atmosphere. The present invention has no particular limitation on the protective atmosphere provided, and any conventional protective atmosphere in the art, such as nitrogen atmosphere, argon atmosphere, etc., can be sufficient.

[0122] In the present invention, the reaction is preferably carried out in a solvent medium. The solvent is preferably anhydrous tetrahydrofuran (THF). In the present invention, the amount of the solvent is not particularly limited, as long as it can fully and evenly dissolve the raw materials.

[0123] In the present invention, the reaction temperature is preferably 55-58°C, specifically 55°C, 56°C, 57°C, 58°C, and more preferably 55°C. The reaction time is preferably 2-2.5 hours, specifically 2 hours, 2.5 hours, and more preferably 2 hours. In the present invention, the reaction is preferably accompanied by magnetic stirring. After the above reaction, lysine-N-carboxylic anhydride is generated in the system, obtaining a reaction solution containing lysine-N-carboxylic anhydride.

[0124] In the present invention, after the above reaction, a post-treatment is preferably performed. The post-treatment includes sedimentation, solid-liquid separation, re-dissolution, extraction, and drying to obtain a crude lysine-N-carboxylic anhydride product; the product is then purified to obtain the lysine-N-carboxylic anhydride product. The sedimentation is preferably performed by adding a precipitant; the precipitant is preferably glacial n-hexane. After sedimentation, the system is separated into layers, and the upper liquid layer and the lower solid layer are precipitated, and solid-liquid separation is performed. The solid-liquid separation method is preferably filtration, specifically filtration using a sand core funnel. After the solid product is obtained, the product is re-dissolved, and the solvent used is preferably glacial ethyl acetate. After re-dissolution, extraction is performed; the extraction solvent used is preferably saturated glacial brine; the extraction can be repeated multiple times. After extraction, the product is placed in a container, anhydrous magnesium sulfate is added, and the product is dried. The drying temperature is preferably -20°C. The magnesium sulfate is then removed, preferably by filtration, and the solvent is removed from the resulting liquid to obtain the crude lysine-N-carboxylic anhydride product. Then, purification is performed, and the purification method is preferably recrystallization purification, and multiple recrystallizations can be performed to purify, thereby obtaining lysine-N-carboxyl anhydride.

[0125] The raw materials used are N(ε)-benzyloxycarbonyl-L-lysine or N(ε)-benzyloxycarbonyl-D-lysine, and both are carried out according to the above process to obtain L-lysine-N-carboxylic anhydride represented by formula (I-1) or D-lysine-N-carboxylic anhydride represented by formula (I-2), respectively.

[0126] About step (B) :

[0127] (B) Preparation of L-glutamic acid-N-carboxylic anhydride: γ-benzyl-L-glutamate is reacted with triphosgene to form L-glutamic acid-N-carboxylic anhydride represented by formula (II).

[0128] The reaction scheme of this step is as follows:

[0129]

[0130] In the present invention, the sources of the raw materials γ-benzyl-L-glutamate (BLG) and triphosgene (BTC) are not particularly limited and can be commercially available products or prepared according to methods known in the art. In the present invention, the molar ratio of γ-benzyl-L-glutamate to triphosgene is preferably (1-2.5):1, specifically 1:1, 1.5:1, 2:1, or 2.5:1, and more preferably 2:1.

[0131] In the present invention, the reaction is preferably carried out in a protective atmosphere. The present invention has no particular limitation on the protective atmosphere provided, and any conventional protective atmosphere in the art, such as nitrogen atmosphere, argon atmosphere, etc., can be sufficient.

[0132] In the present invention, the reaction is preferably carried out in a solvent medium. The solvent is preferably anhydrous tetrahydrofuran (THF). In the present invention, the amount of the solvent is not particularly limited, as long as it can fully and evenly dissolve the raw materials.

[0133] In the present invention, the reaction temperature is preferably 55-58°C, specifically 55°C, 56°C, 57°C, or 58°C, more preferably 55°C. The reaction time is preferably 1.5-2 hours, specifically 1.5 hours or 2 hours, more preferably 1.5 hours. In the present invention, magnetic stirring is preferably used during the reaction. After the above reaction, L-glutamic acid-N-carboxylic anhydride (abbreviated as L-Glu NCA) represented by formula (II) is generated in the system, obtaining a reaction solution containing L-glutamic acid-N-carboxylic anhydride represented by formula (II).

[0134] In the present invention, after the above reaction, a post-treatment is preferably performed. The post-treatment method is the same as the post-treatment method in step (A), and will not be repeated here.

[0135] About step (C) :

[0136] (C) Preparation of a double-terminal polylysine polymer: reacting the lysine-N-carboxylic anhydride with a double-terminal amino polyethylene glycol NH2-PEG-NH2 to form a double-terminal polylysine polymer.

[0137] In the present invention, the lysine-N-carboxylic anhydride is L-lysine-N-carboxylic anhydride represented by formula (I-1) or D-lysine-N-carboxylic anhydride represented by formula (I-2), and the corresponding double-terminal polylysine polymer obtained is a double-terminal polylysine polymer PLL-PEG-PLL represented by formula (I'-1) or a double-terminal polylysine polymer PDL-PEG-PDL represented by formula (I'-2). That is, step (C) comprises: L-lysine-N-carboxylic anhydride represented by formula (I-1) + NH2-PEG-NH2 → double-terminal polylysine polymer PLL-PEG-PLL represented by formula (I'-1), or D-lysine-N-carboxylic anhydride represented by formula (I-2) + NH2-PEG-NH2 → double-terminal polylysine polymer PDL-PEG-PDL represented by formula (I'-2). The reaction routes of the above two reactions are as follows:

[0138]

[0139]

[0140] In the present invention, the source of the double-terminated amino-polyethylene glycol NH2-PEG-NH2 used as a raw material is not particularly limited and can be a commercially available product or prepared according to methods known in the art. The degree of polymerization (x) of the polyethylene glycol units in the double-terminated amino-polyethylene glycol NH2-PEG-NH2 is ≥ 30, preferably 30-95, more preferably 34-91, specifically 34 (corresponding to a PEG molecular weight of 1500) or 91 (corresponding to a PEG molecular weight of 4000), with 91 being more preferred. In the present invention, the double-terminated amino-polyethylene glycol NH2-PEG-NH2 is preferably dehydrated before reacting. The dehydration method is preferably to dissolve the double-terminated amino-polyethylene glycol NH2-PEG-NH2 in toluene and azeotropically remove the water. After dehydration, the toluene is vacuum-pumped and then used.

[0141] In the present invention, when the lysine-N-carboxylic anhydride and the double-terminated amino polyethylene glycol NH2-PEG-NH2 are added, the amount of the lysine-N-carboxylic anhydride added is preferably 100% to 110% of the theoretical amount, that is, the lysine-N-carboxylic anhydride can be in excess of 10%.

[0142] In the present invention, the reaction is preferably carried out in a solvent medium. The solvent is preferably N,N-dimethylformamide (DMF). The solvent is preferably an anhydrous solvent. In the present invention, the ratio of the solvent to the lysine-N-carboxylic anhydride is preferably (9-11) mL:1 g, specifically 9 mL:1 g, 10 mL:1 g, 11 mL:1 g, and more preferably 10 mL:1 g.

[0143] In the present invention, the reaction preferably includes two stages, polymerization reaction and deprotection reaction are carried out sequentially.

[0144] In the present invention, the polymerization reaction temperature is preferably room temperature, 20-26°C, specifically 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, or 26°C, more preferably 25°C. The polymerization reaction duration is preferably 3-4 days, specifically 3 days or 4 days, more preferably 3 days. Preferably, during the polymerization reaction, carbon dioxide is evacuated and nitrogen is introduced daily; the carbon dioxide evacuation lasts for 5-10 minutes per reaction, and nitrogen is introduced after each carbon dioxide evacuation; the carbon dioxide evacuation and nitrogen introduction are performed 1-2 times per day. In the present invention, the polymerization reaction is preferably accompanied by stirring. Through the above reaction, a polymerization reaction occurs between lysine-N-carboxylic anhydride and the double-terminated amino polyethylene glycol NH2-PEG-NH2 to form a polymer. In the present invention, after the above polymerization reaction, the resulting reaction solution is preferably post-treated to obtain a polymer solid.

[0145] In the present invention, after the above-mentioned polymerization reaction, a deprotection reaction is carried out. In the present invention, the deprotection reaction is preferably carried out in the presence of a hydrogen bromide solution. In the present invention, the deprotection reaction is preferably carried out by first dissolving the polymer, then adding the hydrogen bromide solution, and carrying out the deprotection reaction. The solvent used to dissolve the polymer is preferably trifluoroacetic acid. The amount ratio of the solvent to the polymer obtained in the previous step is preferably (10-12) mL:1g, specifically 10 mL:1g, 11 mL:1g, 12 mL:1g, and more preferably 10 mL:1g. After the above-mentioned dissolution, the hydrogen bromide solution is added. The hydrogen bromide solution is preferably an acetic acid solution of hydrogen bromide, that is, a solution formed by dissolving hydrogen bromide in acetic acid. The mass concentration of the hydrogen bromide solution is preferably 33%. In the present invention, the amount ratio of the hydrogen bromide solution to the polymer obtained in the previous step is preferably (3-4) mL:1g, specifically 3 mL:1g, 4 mL:1g, and more preferably 3 mL:1g. In the present invention, the deprotection reaction temperature is preferably room temperature, 20-26°C, specifically 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, or 26°C, more preferably 25°C. The deprotection reaction time is preferably 1-2 hours, specifically 1 hour, 2 hours, and more preferably 1.5 hours. After the deprotection reaction, a double-terminated polylysine polymer is formed in the system, yielding a reaction solution containing the double-terminated polylysine polymer. In the present invention, after the reaction, a post-treatment is preferably performed. The post-treatment preferably includes sedimentation, solid-liquid separation, re-dissolution, dialysis, and drying. The sedimentation is preferably performed by adding a precipitant; the precipitant is preferably glacial ether. After sedimentation, solid-liquid separation is performed. The solid-liquid separation is preferably performed by filtration. After the solid is obtained, it is re-dissolved, preferably in water, more preferably deionized water. After re-dissolution, dialysis and drying are performed. The drying is preferably freeze-drying. After the above post-treatment, a double-terminal polylysine polymer (PLL-PEG-PLL or PDL-PEG-PDL) is obtained.

[0146] In the present invention, in the polymers represented by formula (I'-1) and formula (I'-2), the degree of polymerization x is ≥30, preferably 30-95, more preferably 34-91, specifically 34 (corresponding to a PEG molecular weight of 1500) or 91 (corresponding to a PEG molecular weight of 4000), and more preferably 91. The degree of polymerization m1 is ≥35, preferably 35-85, more preferably 40-80, specifically 40, 50, 60, 70, or 80. The degree of polymerization m2 is ≥35, preferably 35-85, more preferably 40-80, specifically 40, 50, 60, 70, or 80. Preferably, m1 and m2 are equal.

[0147] About step (D) :

[0148] (D) Preparation of a double-terminal polyglutamic acid polymer: reacting L-glutamic acid-N-carboxyl anhydride represented by formula (II) with double-terminal amino polyethylene glycol NH2-PEG-NH2 to form a double-terminal polyglutamic acid polymer represented by formula (II').

[0149] The reaction scheme of this step is as follows:

[0150]

[0151] In the present invention, the source of the double-terminated amino-polyethylene glycol NH2-PEG-NH2 used as a raw material is not particularly limited and can be a commercially available product or prepared according to methods known in the art. The degree of polymerization (x) of the polyethylene glycol units in the double-terminated amino-polyethylene glycol NH2-PEG-NH2 is ≥ 30, preferably 30-95, more preferably 34-91, specifically 34 (corresponding to a PEG molecular weight of 1500) or 91 (corresponding to a PEG molecular weight of 4000), with 91 being more preferred. In the present invention, the double-terminated amino-polyethylene glycol NH2-PEG-NH2 is preferably dehydrated before reacting. The dehydration method is preferably to dissolve the double-terminated amino-polyethylene glycol NH2-PEG-NH2 in toluene and azeotropically remove the water. After dehydration, the toluene is vacuum-pumped and then used.

[0152] In the present invention, when the L-glutamic acid-N-carboxyl anhydride represented by formula (II) and the double-terminal amino polyethylene glycol NH2-PEG-NH2 are added, the amount of the L-glutamic acid-N-carboxyl anhydride represented by formula (II) is preferably added in an amount of 100% to 110% of the theoretical amount, that is, the L-glutamic acid-N-carboxyl anhydride represented by formula (II) can be added in an excess of within 10%.

[0153] In the present invention, the reaction is preferably carried out in a solvent medium. The solvent is preferably N,N-dimethylformamide (DMF). The solvent is preferably an anhydrous solvent. In the present invention, the ratio of the solvent to the L-glutamic acid-N-carboxylic anhydride represented by formula (II) is preferably (9-11) mL:1 g, specifically 9 mL:1 g, 10 mL:1 g, 11 mL:1 g, and more preferably 10 mL:1 g.

[0154] In the present invention, the reaction preferably includes two stages, polymerization reaction and deprotection reaction are carried out sequentially.

[0155] In the present invention, the temperature of the polymerization reaction is preferably room temperature, 20-26°C, specifically 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, and more preferably 25°C. The polymerization reaction time is preferably 3-4 days, specifically 3 days, 4 days, and more preferably 3 days. Preferably, during the polymerization reaction, carbon dioxide is evacuated and nitrogen is introduced daily; wherein the duration of carbon dioxide evacuation is 5-10 minutes per time, and nitrogen is introduced after each carbon dioxide evacuation; the above-mentioned carbon dioxide evacuation and nitrogen introduction operations are performed 1-2 times per day. In the present invention, the polymerization reaction is preferably accompanied by stirring. Through the above reaction, a polymerization reaction occurs between L-glutamic acid-N-carboxylic anhydride represented by formula (II) and the double-terminated amino polyethylene glycol NH2-PEG-NH2 to form a polymer. In the present invention, after the above polymerization reaction, the resulting reaction solution is preferably post-treated to obtain a polymer solid.

[0156] In the present invention, after the above-mentioned polymerization reaction, a deprotection reaction is carried out. In the present invention, the deprotection reaction is preferably carried out in the presence of a hydrogen bromide solution. In the present invention, the implementation process of the deprotection reaction preferably includes: first dissolving the polymer, then adding a hydrogen bromide solution, and carrying out a deprotection reaction. Among them, the solvent used to dissolve the polymer is preferably trifluoroacetic acid. The amount ratio of the solvent to the polymer obtained in the previous step is preferably (10~12)mL:1g, specifically 10mL:1g, 11mL:1g, 12mL:1g, and more preferably 10mL:1g. After the above-mentioned dissolution, a hydrogen bromide solution is added. The hydrogen bromide solution is preferably an acetic acid solution of hydrogen bromide, that is, a solution formed by hydrogen bromide dissolved in acetic acid. The mass concentration of the hydrogen bromide solution is preferably 33%. In the present invention, the ratio of the hydrogen bromide solution to the polymer obtained in the previous step is preferably (3-4) mL:1 g, specifically 3 mL:1 g, 4 mL:1 g, and more preferably 3 mL:1 g. In the present invention, the temperature of the deprotection reaction is preferably room temperature, 20-26°C, specifically 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, and more preferably 25°C. The deprotection reaction time is preferably 1-2 hours, specifically 1 hour, 2 hours, and more preferably 1.5 hours. After the deprotection reaction, a double-terminated polyglutamic acid polymer of formula (II') is formed in the system, obtaining a reaction solution containing the double-terminated polyglutamic acid polymer of formula (II'). In the present invention, after the reaction, post-treatment is preferably performed. The post-treatment preferably includes sedimentation, solid-liquid separation, redissolution, dialysis, and drying. The sedimentation is preferably performed by adding a precipitant; the precipitant is preferably glacial ether. After sedimentation, solid-liquid separation is performed. The solid-liquid separation method is preferably suction filtration. After obtaining the solid, the solid is redissolved, preferably in DMF. After redissolution, the solid is dialyzed and dried, preferably by freeze-drying. Following the above post-treatment, a double-terminated polyglutamic acid polymer (PGlu-PEG-PGlu) of formula (II') is obtained.

[0157] In the present invention, in the polymer represented by formula (II'), the degree of polymerization x is ≥30, preferably 30-95, more preferably 34-91, specifically 34 (corresponding to a PEG molecular weight of 1500) or 91 (corresponding to a PEG molecular weight of 4000), and more preferably 91. The degree of polymerization m1 is ≥35, preferably 35-85, more preferably 40-80, specifically 40, 50, 60, 70, or 80. The degree of polymerization m2 is ≥35, preferably 35-85, more preferably 40-80, specifically 40, 50, 60, 70, or 80. Preferably, m1 and m2 are the same.

[0158] In the present invention, more preferably, m1 in the double-terminal polyglutamic acid polymer represented by formula (II') is the same as m1 in the double-terminal polylysine polymer obtained in step (C), and m2 in the double-terminal polyglutamic acid polymer represented by formula (II') is the same as m2 in the double-terminal polylysine polymer obtained in step (C); further preferably, m1 and m2 are also the same.

[0159] About step (E) :

[0160] (E) Preparation of hydrogel: including steps E1 to E3.

[0161] Regarding step E1:

[0162] E1: dissolving the double-terminated polylysine polymer obtained in step (C) in water, adjusting the pH value, dialyzing, drying, and then mixing with a solvent to prepare a double-terminated polylysine polymer solution.

[0163] In the present invention, the water is preferably deionized water. The concentration of the resulting solution obtained by dissolving the double-terminated polylysine polymer obtained in step (C) in water is preferably 5% to 20% (w / v), specifically 5%, 10%, 15%, 20%, and more preferably 10%. The pH regulator used to adjust the pH is preferably an acid, more preferably hydrochloric acid. The concentration of the acid is preferably 0.1 to 1M, specifically 0.1M, 0.2M, 0.3M, 0.4M, 0.5M, 0.6M, 0.7M, 0.8M, 0.9M, 1.0M, and more preferably 0.1M. The pH is preferably adjusted to 7.0 to 7.8. The present invention achieves better in vivo adaptation at these pH values, specifically 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, or 7.8, and more preferably 7.4. After adjusting the pH, dialysis is performed, specifically in deionized water; the dialysis is preferably performed to a neutral pH (pH 7.3-7.5). After dialysis, drying is performed, preferably freeze-drying.

[0164] In the present invention, after drying, the resulting solid is mixed with a solvent to prepare a double-terminated polylysine polymer solution. The solvent is preferably a PBS buffer solution. The concentration of the prepared double-terminated polylysine polymer solution is preferably 1 to 20 mmol / L, specifically 1 mmol / L, 4.25 mmol / L, 5 mmol / L, 10 mmol / L, 15 mmol / L, or 20 mmol / L.

[0165] In the present invention, the double-terminal polylysine polymer PLL-PEG-PLL represented by formula (I'-1) and the double-terminal polylysine polymer PDL-PEG-PDL represented by formula (I'-2) are prepared into double-terminal polylysine polymer solutions according to the above process.

[0166] Regarding step E2:

[0167] E2: The double-terminated polyglutamic acid polymer obtained in step (D) is dissolved in water, the pH value is adjusted, dialyzed, dried, and then mixed with a solvent to prepare a double-terminated polyglutamic acid polymer solution.

[0168] In the present invention, the water is preferably deionized water. The concentration of the resulting solution obtained by dissolving the double-terminated polyglutamic acid polymer obtained in step (D) in water is preferably 5% to 20% (w / v), specifically 5%, 10%, 15%, 20%, and more preferably 10%. The pH regulator used to adjust the pH is preferably an alkaline solution, more preferably a NaOH solution. The concentration of the alkaline solution is preferably 0.1 to 1M, specifically 0.1M, 0.2M, 0.3M, 0.4M, 0.5M, 0.6M, 0.7M, 0.8M, 0.9M, 1.0M, and more preferably 0.1M. The pH is preferably adjusted to 7.0 to 7.8. The present invention achieves better in vivo adaptation at these pH values, specifically 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, or 7.8, with 7.4 being more preferred. After adjusting the pH, dialysis is performed, specifically in deionized water; the dialysis is preferably performed to a neutral pH (pH 7.3-7.5). After dialysis, drying is performed, preferably freeze-drying.

[0169] In the present invention, after drying, the resulting solid is mixed with a solvent to prepare a double-terminated polyglutamic acid polymer solution. The solvent is preferably a PBS buffer solution. The concentration of the prepared double-terminated polyglutamic acid polymer solution is preferably 1 to 20 mmol / L, specifically 1 mmol / L, 4.25 mmol / L, 5 mmol / L, 10 mmol / L, 15 mmol / L, or 20 mmol / L.

[0170] Regarding Step E3:

[0171] E3: The double-terminal poly-lysine polymer solution obtained in step E1 is mixed with the double-terminal poly-glutamic acid polymer solution obtained in step E2 to obtain an ionically cross-linked hydrogel.

[0172] In the present invention, the process of mixing the two solutions preferably includes: injecting the double-ended polylysine polymer solution obtained in step E1 and the double-ended polyglutamic acid polymer solution obtained in step E2 into an AB rubber tube syringe, pushing the syringe plunger, and mixing the two solutions into a gel to obtain an ionically cross-linked hydrogel. In the present invention, the double-ended polylysine polymer solution obtained in step E1 is positively charged, and the double-ended polyglutamic acid polymer solution obtained in step E2 is negatively charged. When the two are mixed, they quickly form a gel under the action of positive and negative charges (NH 3＋and COO - physical cross-linking between the two), thereby forming a uniformly mixed ion-crosslinked hydrogel.

[0173] In the present invention, when the double-ended polylysine polymer solution obtained in step E1 is mixed with the double-ended polyglutamic acid polymer solution obtained in step E2, the number of amino groups in the double-ended polylysine polymer and the number of carboxyl groups in the double-ended polyglutamic acid polymer are preferably controlled to be similar, and the molar ratio is preferably 1:(0.8-1.2), specifically 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, and more preferably 1:1. By controlling the number of amino groups in the double-ended polylysine polymer and the number of carboxyl groups in the double-ended polyglutamic acid polymer to be similar, the positive and negative charges of the two solutions are offset when mixed, maintaining electrical neutrality; and the formed ionically cross-linked hydrogel is more stable and regular; a small amount of free cations will not harm the body and will have some antibacterial effect, but excessive cations or too high or too low pH will produce cytotoxicity, so it is necessary to try to ensure that the molar number of the above two groups is similar. To ensure that the number of amino groups in the double-terminated polylysine polymer is similar to the number of carboxyl groups in the double-terminated polyglutamic acid polymer, this can be achieved by controlling the degree of polymerization of the double-terminated polylysine polymer and the double-terminated polyglutamic acid polymer at both ends to be the same (including the same degree of polymerization at both ends of each polymer itself, and the same degree of polymerization at both ends of the two polymers). Then, when preparing the polymer solution, the molar concentration of the double-terminated polylysine polymer solution and the double-terminated polyglutamic acid polymer solution obtained in step E2 are controlled to be the same. Finally, when preparing the hydrogel, the volume of the double-terminated polylysine polymer solution and the double-terminated polyglutamic acid polymer solution taken are controlled to be the same.

[0174] The present invention also provides a polyamino acid hydrogel prepared by the preparation method described in the above technical solution.

[0175] The polyamino acid hydrogel provided by the present invention has the characteristics of low gelation concentration, rapid gelation, good biocompatibility and biodegradability, and has suitable strength and porosity to simulate natural nerve ECM. Polylysine can induce macrophages to polarize to the M2 phenotype, has anti-inflammatory and repair-promoting effects, and the D-type induction effect is more obvious than the L-type. The degradation product of polyglutamic acid is a neurotransmitter, which has a nutritional support effect. The two avoid the cytotoxicity of polylysine cations through positive and negative electrical cross-linking. The hydrogel catheter avoids the problem of easy collapse of the hollow catheter, and achieves better peripheral nerve defect repair effects through the physical and chemical properties of the filler itself.

[0176] The present invention also provides a method for preparing a hydrogel catheter, comprising the following steps:

[0177] S1, dissolving a polymer in a solvent to obtain a spinning solution; then, performing electrospinning to obtain a polymer film;

[0178] S2, forming the polymer film into a tube to obtain a catheter;

[0179] S3, mixing the double-ended poly-lysine polymer solution and the double-ended poly-glutamic acid polymer solution into a gel in the catheter to obtain a hydrogel catheter;

[0180] The double-terminal poly-lysine polymer solution and the double-terminal poly-glutamic acid polymer solution are prepared by referring to the preparation method described in the above technology.

[0181] Regarding step S1:

[0182] In the present invention, the polymer is preferably poly(lactic acid-co-glycolic acid). The solvent is preferably at least one of hexafluoroisopropanol, dichloromethane (DCM), and dimethylformamide (DMF). The polymer to solvent ratio is preferably 4.0 g:(32-48) mL, specifically 4.0 g:32 mL, 4.0 g:35 mL, 4.0 g:40 mL, 4.0 g:45 mL, or 4.0 g:48 mL. The polymer and solvent are stirred until fully dissolved and no phase separation occurs, thereby obtaining a spinning solution.

[0183] In the present invention, after obtaining the spinning solution, electrospinning is performed. Oriented electrospinning is a method for producing highly oriented fibers using electrospinning technology. The polymer solution or melt is stretched into fibers using electrostatic forces, which are then drawn onto rollers to align the fibers in a specific direction. Specifically, the spinning solution is drawn into a syringe and steadily placed on a stepper. The advancement speed is preferably 0.1-0.2 mm / min, more preferably 0.2 mm / min. Electrospinning is then performed using an electrospinning machine. The speed of the electrospinning machine is preferably controlled between 1400 and 2000 rpm. At these speeds, a spinning membrane with a certain degree of orientation can be obtained. Specifically, the speed can be 1400 rpm, 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm, 1900 rpm, or 2000 rpm. The operating voltage of the electrospinning machine is preferably 14 kV. Under these operating conditions, a polymer membrane is produced. This membrane has orientation and a certain strength, and serves as the outer layer of the nerve conduit surrounding the hydrogel filler.

[0184] Regarding step S2:

[0185] In the present invention, the electrospun membrane is preferably formed into a tube by winding it into a tube. Specifically, the polymer film obtained in step S1 is cut into rectangular shapes, and the polymer film is rolled into a tube using a cylindrical mold as an axis, and the edges are fixed to obtain a catheter.

[0186] When the polymer film is cut into rectangles, the parallel-oriented side is the length side, and the perpendicular-oriented side is the width side (the lengths of the length side and the width side may be the same or different). The parallel-oriented side corresponds to the catheter length, and there are no special restrictions on its cutting size. It can be made into various lengths according to the actual application scenario (for example, in a certain experiment of the present invention, because the length of the sciatic nerve defect model of the rat is 10 mm, it is appropriate to make a nerve catheter with a length of 11-12 mm, including the suture sites at both ends and the nerve stump, so the parallel-oriented side is cut to 11 mm). The perpendicular-oriented side is larger than the circumference of the mold, specifically >5 mm; the length of this side can be determined specifically based on the expected thickness (number of layers) of the catheter to be produced (for example, in a certain experiment of the present invention, a cylindrical mold with a diameter of 1.5 mm is used as the axis to roll it into a tube. The length of the tube after two rolls is approximately 10 mm. It can also be rolled 1 turn, or 3 turns or more. Therefore, its length can be determined based on the mold size and the number of winding layers). The outer diameter of the cylindrical mold can be determined according to the actual application scenario (for example, in an experiment of the present invention, the outer diameter of the cylindrical mold is controlled to be 1-2 mm, preferably 1.5 mm, in order to adapt to the diameter of the sciatic nerve of rats in the experiment). After all the dimensions are determined, the spinning membrane is rolled up along the parallel oriented axis to form a conduit, such as Figure 1 As shown, where b is the length of the parallel orientation and a is the diameter of the catheter.

[0187] In the present invention, after the tube is wound, the edges are fixed. In the present invention, it is preferred to fix the edges by sewing them to stabilize the catheter.

[0188] Regarding step S3:

[0189] In the present invention, the double-terminal poly-lysine polymer solution and the double-terminal poly-glutamic acid polymer solution are prepared by referring to the preparation method described in the above technology, which will not be repeated here.

[0190] In the present invention, the implementation process of mixing the double-ended polylysine polymer solution and the double-ended polyglutamic acid polymer solution into a gel in the catheter preferably includes: respectively loading the double-ended polylysine polymer solution and the double-ended polyglutamic acid polymer solution into an AB rubber tube syringe, connecting the front end of the syringe to the catheter, pushing the syringe push rod to allow the solution to enter the catheter, and mixing the double-ended polylysine polymer solution and the double-ended polyglutamic acid polymer solution into a gel in the catheter to obtain a hydrogel catheter. The front end of the syringe can be connected to the catheter by inserting a needle connected to the front end of the syringe into the catheter. After the double-ended polylysine polymer solution and the double-ended polyglutamic acid polymer solution are pushed into the catheter, they are fully mixed, quickly gelled, and fill the catheter to obtain a hydrogel catheter. The hydrogel catheter is a catheter based on polyamino acid hydrogel, specifically a nerve catheter based on polyamino acid hydrogel.

[0191] The present invention also provides a hydrogel catheter produced by the preparation method described in the above technical solution. Specifically, the present invention provides a nerve catheter comprising a polyamino acid hydrogel interior and an electrospun membrane exterior. The hydrogel catheter described herein is a polyamino acid hydrogel-based nerve catheter, specifically a nerve catheter for peripheral nerve defect repair. The exterior of this nerve catheter is composed of an oriented poly(lactic-co-glycolic acid) (PLGA) electrospun membrane, while the interior is filled with a biocompatible, biodegradable chiral polyamino acid hydrogel, which provides support for the catheter. The hydrogel itself and its degradation products mimic the natural extracellular matrix (ECM) in terms of nutrient, contact, guidance, and immune microenvironment regulation, achieving improved peripheral nerve defect repair results.

[0192] Currently, most existing nerve catheters are hollow structures. The effect of promoting peripheral nerve regeneration is achieved through improvements in the design, synthesis and preparation processes of catheter materials, as well as physical and chemical modifications of the inner wall of the catheter. However, hollow catheters lack supporting force and are prone to collapse when implanted in the body, and are even more unable to simulate the effects of natural nerve ECM. The present invention fills the catheter with a biocompatible and biodegradable polyamino acid hydrogel, which supports the catheter and simulates the effects of natural nerve ECM on cell nutrition support, contact guidance and regulation of the immune microenvironment during the regeneration process, thereby achieving better peripheral nerve defect repair effects. The present invention improves the efficiency of nerve regeneration by filling the catheter with hydrogel and utilizing the material’s own physical and chemical cues to regulate macrophage polarization, Schwann cell migration and differentiation, and accelerate axon growth.

[0193] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0194] Example 1

[0195] 1. Preparation of polyamino acid hydrogel

[0196] (A) Preparation of chiral lysine-N-carboxylic anhydride

[0197] A.1 Preparation of L-lysine-N-carboxylic anhydride:

[0198] The reaction route is as follows:

[0199]

[0200] The preparation process is as follows:

[0201] A three-necked round-bottom flask was vacuum-dried and then purged with nitrogen three times to ensure the flask was dry and anhydrous. Under a nitrogen atmosphere, 300 mL of anhydrous tetrahydrofuran (THF), 20 g of N(ε)-benzyloxycarbonyl-L-lysine (ZLL), and 12 g of triphosgene (BTC) were added. The mixture was stirred in an oil bath at 55°C for 2 h with magnetic stirring to obtain a reaction solution containing lysine-N-carboxylic anhydride. The nitrogen flow rate was increased to reduce the reaction system to 50 mL. Ice-cold n-hexane was allowed to settle, and the supernatant was filtered using a fritted funnel. The solution was then re-dissolved in glacial ethyl acetate and extracted seven times with saturated ice-cold brine. The solution was then placed in an Erlenmeyer flask, an appropriate amount of anhydrous magnesium sulfate was added, and the solution was dried overnight at -20°C. The next day, the magnesium sulfate was removed by filtration using a G4 fritted funnel. The solvent was then removed from the filtrate using a vacuum pump connected to a cold trap to obtain lysine NCA solid. The product was then recrystallized and purified several times to obtain a white needle-shaped solid product, namely L-lysine-N-carboxylic anhydride (abbreviated as L-Lys NCA) represented by formula (I-1).

[0202] A.2 Preparation of D-lysine-N-carboxylic anhydride:

[0203] The reaction route is as follows:

[0204]

[0205] The preparation process is as follows:

[0206] The process is carried out in accordance with step A.1, except that the raw material N(ε)-benzyloxycarbonyl-L-lysine (ZLL) is replaced by N(ε)-benzyloxycarbonyl-D-lysine (ZDL), thereby obtaining D-lysine-N-carboxylic anhydride (abbreviated as D-Lys NCA) represented by formula (I-2).

[0207] (B) Preparation of L-glutamic acid-N-carboxylic anhydride

[0208] The reaction route is as follows:

[0209]

[0210] The preparation process is as follows:

[0211] The process was carried out in accordance with step A.1, except that the raw material N(ε)-benzyloxycarbonyl-L-lysine (ZLL) was replaced with γ-benzyl-L-glutamate (BLG). The reaction was carried out in a three-necked round-bottom flask for 1.5 h to obtain L-glutamic acid-N-carboxylic anhydride (abbreviated as L-Glu NCA) represented by formula (II).

[0212] (C) Preparation of double-terminated polylysine polymers

[0213] C.1 Preparation of double-terminal polylysine polymer PLL-PEG-PLL represented by formula (I'-1):

[0214] The reaction route is as follows:

[0215]

[0216] The preparation process is as follows:

[0217] Dissolve 1.0 g of double-terminated amino-polyethylene glycol NH2-PEG-NH2 (0.25 mmol, PEG degree of polymerization x = 91) in 140 mL of toluene and remove water azeotropically. After evacuating the toluene using a vacuum pump, add 120 mL of anhydrous N,N-dimethylformamide (DMF) and 13.475 g of L-Lys-NCA (44 mmol) obtained in Step A.1, sequentially. Stir at 25°C for 3 days, evacuating carbon dioxide and purging with nitrogen once daily. The resulting reaction solution is then precipitated with an excess of glacial ether and dried under vacuum to obtain a white solid polymer, which is weighed. The resulting polymer is then dissolved in trifluoroacetic acid (trifluoroacetic acid: polymer ratio: 10 mL: 1 g), followed by the addition of a 33% solution of hydrogen bromide in acetic acid (3 mL: 1 g of polymer) and allowed to react for 1.5 h for deprotection. After the reaction, the mixture was precipitated with excess glacial ether and filtered to obtain a solid. The solid was dissolved in water, dialyzed against deionized water for 3 days, and freeze-dried to obtain a double-terminal polylysine polymer (PLL-PEG-PLL, degree of polymerization x=91, m1=m2=80) represented by formula (I'-1). Its H NMR spectrum is shown in Figure 1. Figure 2 shown.

[0218] C.2 Preparation of double-terminal polylysine polymer PDL-PEG-PDL represented by formula (I'-2):

[0219] The reaction route is as follows:

[0220]

[0221] The preparation process is as follows:

[0222] The same process as in step C.1 was followed, except that the L-Lys-NCA obtained in step A.1 was replaced with the D-Lys NCA obtained in step A.2, thereby obtaining a double-terminal polylysine polymer (PDL-PEG-PDL, degree of polymerization x=91, m1=m2=80) represented by formula (I'-2). Its H NMR spectrum is shown in FIG. Figure 3 shown.

[0223] (D) Preparation of double-terminated polyglutamic acid polymers

[0224] The reaction route is as follows:

[0225]

[0226] The preparation process is as follows:

[0227] Dissolve 1.0 g of double-terminated amino-polyethylene glycol NH2-PEG-NH2 (0.25 mmol, PEG degree of polymerization x = 91) in 140 mL of toluene and remove water azeotropically. After evacuating the toluene using a vacuum pump, add 120 mL of anhydrous N,N-dimethylformamide (DMF) and 11.583 g of L-Glu NCA (44 mmol) obtained in Step B, sequentially. Stir at 25°C for 3 days, evacuating carbon dioxide and purging with nitrogen once daily. The resulting reaction solution is then precipitated with an excess of glacial ether and dried under vacuum to obtain a white solid polymer, which is weighed. The resulting polymer is then dissolved in trifluoroacetic acid (trifluoroacetic acid: polymer ratio: 10 mL: 1 g), followed by the addition of a 33% hydrogen bromide solution in acetic acid (3 mL: 1 g of polymer) for 1.5 h for deprotection. After the reaction, the mixture was precipitated with excess glacial ether and filtered to obtain a solid. The solid was dissolved in DMF, dialyzed against deionized water for 3 days, and freeze-dried to obtain a double-terminal polyglutamic acid polymer of formula (II') (PGlu-PEG-PGlu, degree of polymerization x = 91, m1 = m2 = 80). Its H NMR spectrum is as follows: Figure 4 shown.

[0228] (E) Preparation of hydrogel

[0229] E1: Dissolve the double-terminated polylysine polymer PLL-PEG-PLL of formula (I'-1) obtained in step C.1 in deionized water (solution concentration: 10% w / v). Adjust the pH to 7.4 with 0.1 M hydrochloric acid, dialyze against deionized water until neutral, and freeze-dry. Then, dissolve in 0.01 M PBS buffer (pH = 7.4) to obtain a solution of PLL-PEG-PLL of formula (I'-1) (concentration: 4.25 mmol / L, calculated based on a hydrogel concentration of 10 wt%).

[0230] The above process is carried out, except that the double-terminal polylysine polymer PLL-PEG-PLL represented by formula (I'-1) is replaced by the double-terminal polylysine polymer PDL-PEG-PDL represented by formula (I'-2), thereby obtaining a solution of PDL-PEG-PDL represented by formula (I'-2) (concentration is the same as above).

[0231] E2: Dissolve the double-terminated polyglutamic acid polymer PGlu-PEG-PGlu obtained in step (D) in deionized water (solution concentration: 10% w / v), adjust the pH to 7.4 with 0.1 M NaOH solution, dialyze against deionized water until neutral, and freeze-dry. Then, dissolve in 0.01 M PBS buffer (pH = 7.4) to obtain a PGlu-PEG-PGlu solution of formula (II') (concentration: same as in step E1).

[0232] E3: Take equal volumes of the PLL-PEG-PLL solution represented by formula (I'-1) and the PGlu-PEG-PGlu solution represented by formula (II') and inject them into the AB rubber tube syringe respectively. Push the syringe plunger. The two solutions with opposite charges quickly gel under the action of positive and negative charges to form a uniformly mixed ion-crosslinked hydrogel (denoted as hydrogel 1).

[0233] Equal volumes of the PDL-PEG-PDL solution represented by formula (I'-2) and the PGlu-PEG-PGlu solution represented by formula (II') were injected into the AB rubber tube syringe respectively. The syringe plunger was pushed. The two solutions with opposite charges quickly gelled under the action of positive and negative charges to form a uniformly mixed ion-crosslinked hydrogel (denoted as hydrogel 2).

[0234] 2. Product testing:

[0235] (1) Circular dichroism test

[0236] The circular dichroism spectra of the aqueous solution of PLL-PEG-PLL represented by formula (I'-1), the aqueous solution of PDL-PEG-PDL represented by formula (I'-2), and the aqueous solution of PGlu-PEG-PGlu represented by formula (II') are as follows: Figure 5 As shown (the labeled PLL in the figure corresponds to PLL-PEG-PLL shown in formula (Ⅰ'-1) , the labeled PDL corresponds to PDL-PEG-PDL shown in formula (Ⅰ'-2) , and the labeled PGlu corresponds to PGlu-PEG-PGlu shown in formula (Ⅱ') ), circular dichroism analysis shows the secondary structures of the three polymers in aqueous solution, among which PLL-PEG-PLL shown in formula (Ⅰ'-1) and PDL-PEG-PDL shown in formula (Ⅰ'-2) are symmetrically distributed.

[0237] (2) Rheological test of hydrogel

[0238] Rheological tests were performed on hydrogels of different concentrations. Specifically, rheological tests were performed on PLL+PGlu hydrogels (i.e., hydrogel 1) and PDL+PGlu hydrogels (i.e., hydrogel 2) of different concentrations to investigate the changes in the modulus of the hydrogels of various concentrations (3wt%, 5wt%, 8wt%, 10wt%) over time. The results are shown in Figure 2. Figure 6 As shown, Figure 6 A is the rheological test graph of PLL+PGlu hydrogel with different concentrations. Figure 6 B is the rheological test graph of PDL+PGlu hydrogels with different concentrations, where G' is the storage modulus and G" is the loss modulus.

[0239] Depend on Figure 6As can be seen, the hydrogels gel quickly and stably at relatively low concentrations (as low as 3 wt%). They exhibit high strength, with modulus increasing with concentration (at 3 wt%, the storage modulus G' of hydrogel 1 and hydrogel 2 is above 400 Pa and 500 Pa, respectively, with higher moduli at higher concentrations). These moduli match the modulus of neural ECM. Rheological testing identified a concentration range of hydrogels with a modulus similar to that of the surrounding neural ECM.

[0240] (3) SEM characterization of hydrogel

[0241] The 3 wt% hydrogel in item (2) was confirmed by cryo-scanning electron microscopy to have a regularly arranged porous network structure with a pore size of 10-15 μm, which is suitable for cell growth. Figure 7 As shown, Figure 7 A is the SEM image of PLL+PGlu hydrogel, Figure 7 B is the SEM image of PDL+PGlu hydrogel.

[0242] (4) Verification of hydrogel biological function

[0243] Macrophages were first induced into M1 phenotype using lipopolysaccharide (LPS), and then the two hydrogels were added and co-cultured for 24 hours, and flow cytometry was performed. Figure 8 The flow cytometric results of the hydrogel's regulation of macrophage (RAW 264.7) phenotype are shown in Figure 2. Figure 8 A is a quantitative analysis of the proportion of M1 phenotype after co-culture of different materials. Figure 8 B is a quantitative analysis of the proportion of M2 phenotype. Figure 8 Figure C shows the analysis of the relative ratio of M2 to M1. Flow cytometry results show that compared with the control group, both polyamino acid hydrogels (i.e., hydrogel 1 and hydrogel 2) reduced the proportion of M1 while increasing the proportion of M2. This demonstrates the hydrogel's ability to modulate macrophage phenotype and reverse inflammation in vitro, further demonstrating its ability to mimic the effects of native neural ECM, regulate the immune microenvironment, inhibit inflammation, and achieve peripheral nerve defect repair. Furthermore, the M2 / M1 ratio in the hydrogel group was significantly increased, with the D-type increasing more significantly than the L-type, indicating that the PGlu+PDL hydrogel has a stronger advantage in inhibiting M1 and promoting M2 polarization.

[0244] Example 2

[0245] 1. Preparation of hydrogel catheter

[0246] S1. Stir 4.0g of polylactic acid-glycolic acid in 40mL of hexafluoroisopropanol in a closed container overnight to fully dissolve until there is no phase separation to obtain a spinning solution. The spinning solution is drawn into a syringe and placed steadily on a stepper with a propulsion speed of 0.2mm / min. The distance between the needle tip and the roller collector coated with copper foil is 15cm. The electrospinning machine is operated at 1600rpm and 14kV to prepare a polylactic acid-glycolic acid film, i.e., an oriented PLGA film. The film has orientation and a certain strength, and can be used as the outer layer of a nerve conduit to wrap around a hydrogel filler. The scanning electron microscope image of the film is shown below. Figure 9 The tensile test stress-strain curve of the membrane is shown in Figure 10 The material has good initial rigidity and toughness, among which the parallel orientation direction (Radial) has a higher elastic modulus and tensile strength, while the perpendicular orientation direction (Tangential) has higher ductility and flexibility.

[0247] S2. Cut the oriented PLGA membrane obtained in step S1 into an 11 mm x 10 mm rectangle, with the parallel-oriented side measuring 11 mm and the perpendicular-oriented side measuring 10 mm. Using the 11 mm parallel-oriented side as the base and a 1.5 mm outer diameter cylindrical mold as the axis, roll the PLGA membrane into a tube (approximately two turns). Suture the edges with 8-0 suture to secure the catheter.

[0248] S3. Take the PLL-PEG-PLL solution represented by formula (I'-1) obtained in step E1 of Example 1 and the PGlu-PEG-PGlu solution represented by formula (II') obtained in step E2 of Example 1, and load them into an AB rubber tube syringe in equal volumes. Connect an 18G needle to the front end and insert it into the catheter. Push the syringe plunger. The two solutions are fully mixed in the tube and quickly form a gel, filling the catheter, i.e., a hydrogel catheter (referred to as hydrogel catheter 1).

[0249] The above process was followed, except that the solution of PLL-PEG-PLL represented by formula (I'-1) was replaced by the solution of PDL-PEG-PDL represented by formula (I'-2) obtained in step E1 of Example 1, to obtain a hydrogel catheter (denoted as hydrogel catheter 2).

[0250] 2. Product testing

[0251] (1) Appearance

[0252] The catheter obtained in step S1 and the hydrogel catheter obtained in step S3 are as follows Figure 11 As shown, Figure 11 A is the main view of the catheter obtained in step S1, Figure 11 B is a side view of the catheter obtained in step S1, Figure 11 C is a side view of the hydrogel catheter obtained in step S3.

[0253] (2) In vivo nerve repair effect test of polyamino acid hydrogel catheter

[0254] A 10 mm left sciatic nerve defect model was established in rats. An 11 mm hollow PLGA conduit (Hollow group) or a PLGA conduit filled with PLL+PGlu or PDL+PGlu hydrogel (PLL+PGlu group / PDL+PGlu group) was used to bridge the nerve stump. Autologous nerve grafting (Autograft group) served as the control group. Lower limb motor function and regenerated nerve histology were evaluated three months after surgery.

[0255] Gait analysis chart can directly reflect the recovery of lower limb motor function after surgery, such as Figure 12 As shown, Figure 12 A is the footprint of both hind limbs of rats in the autologous transplantation group; Figure 12 B is the footprint diagram of the PLGA empty catheter group; Figure 12 C is the footprint of the internally filled PLL+PGlu hydrogel group; Figure 12 D is the footprint of the internally filled PDL+PGlu hydrogel group. Figure 12 As can be seen from A, the autologous transplantation as the positive control group had the best recovery, with the toes stretched wider. Figure 12 As can be seen from B, the ATC group had severe flexion contracture, limited toe extension, and ankle joint compensation landing, resulting in longer footprint length, indicating that the recovery of lower limb motor function was the worst; Figure 12 C and Figure 12 It can be seen from D that the hydrogel group is significantly better than the empty tube group and slightly worse than the autologous transplantation group, indicating its effect in promoting nerve repair.

[0256] Transmission electron microscopy (TEM) images of regenerated nerve tissue Figure 13 As shown, Figure 13 A1, A2, and A3 are TEM images of the autologous transplantation group at 2000x, 6000x, and 25000x magnifications, respectively; Figure 13 Figures B1, B2, and B3 are TEM images of the PLGA empty catheter group at 2000x, 6000x, and 25000x magnifications, respectively; Figure 13 C1, C2, and C3 are TEM images of the internally filled PLL+PGlu hydrogel group at 2000x, 6000x, and 25000x magnifications, respectively; Figure 13D1, D2, and D3 are TEM images of the internally filled PDL+PGlu hydrogel group at 2000x, 6000x, and 25000x magnifications, respectively. Myelin regeneration is a key step in nerve regeneration. In the early stages, Schwann cells guide the direction of axon growth, while in the later stages, the degree of axon myelination and myelin thickness represent the progress and effectiveness of nerve regeneration. It can be seen that the hydrogel group outperformed the empty tube group in terms of the number of regenerated axons, the diameter of myelinated axons, and the thickness of myelin sheaths, and was slightly inferior to the autologous transplant group, verifying the in vivo nerve repair effect from a histological perspective.

[0257] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal description of the claims, or if they include equivalent structural elements that are not substantially different from the literal description of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing a polyamino acid hydrogel, characterized in that: The following steps are involved: (A) Preparation of chiral lysine-N-carboxylic anhydride: N(ε)-benzyloxycarbonyl-lysine reacts with triphosgene to form lysine-N-carboxylic anhydride; in, The N(ε)-benzyloxycarbonyl-lysine is N(ε)-benzyloxycarbonyl-L-lysine or N(ε)-benzyloxycarbonyl-D-lysine; The obtained lysine-N-carboxyl internal anhydride is L-lysine-N-carboxyl internal anhydride represented by formula (I-1) or D-lysine-N-carboxyl internal anhydride represented by formula (I-2); (B) Preparation of L-glutamic acid-N-carboxylic anhydride: γ-Benzyl-L-glutamate reacts with triphosgene to form L-glutamic acid-N-carboxylic anhydride represented by formula (II); (C) Preparation of double-terminated polylysine polymers: reacting the lysine-N-carboxylic anhydride with double-terminated amino polyethylene glycol NH2-PEG-NH2 to form a double-terminated polylysine polymer; in, The lysine-N-carboxyl internal anhydride is L-lysine-N-carboxyl internal anhydride represented by formula (I-1) or D-lysine-N-carboxyl internal anhydride represented by formula (I-2); The obtained double-terminal polylysine polymer is a double-terminal polylysine polymer PLL-PEG-PLL represented by formula (I'-1) or a double-terminal polylysine polymer PDL-PEG-PDL represented by formula (I'-2); (D) Preparation of double-terminated polyglutamic acid polymers: The L-glutamic acid-N-carboxyl anhydride represented by formula (II) is reacted with double-terminal amino polyethylene glycol NH2-PEG-NH2 to form a double-terminal polyglutamic acid polymer PGlu-PEG-PGlu represented by formula (II'); (E) Preparation of hydrogel: E1: dissolving the double-terminated polylysine polymer obtained in step (C) in water, adjusting the pH value, dialyzing, drying, and then mixing with a solvent to prepare a double-terminated polylysine polymer solution; wherein the pH regulator used to adjust the pH value is an acid; E2: dissolving the double-terminated polyglutamic acid polymer obtained in step (D) in water, adjusting the pH value, dialyzing, drying, and then mixing with a solvent to prepare a double-terminated polyglutamic acid polymer solution; wherein the pH adjusting agent used is an alkali solution; E3: mixing the double-terminal poly-lysine polymer solution obtained in step E1 with the double-terminal poly-glutamic acid polymer solution obtained in step E2 to obtain an ionically cross-linked hydrogel; ， ； Formula (I-1) Formula (I-2); Formula (II); ， ； Formula (I'-1) Formula (I'-2); Formula (II'); Among them, the degree of polymerization x≥30, m1≥35, m2≥35; There is no particular restriction on the order of the steps in each step.

2. The preparation method according to claim 1, characterized in that In step (A), the reaction temperature is 55-58°C; In step (B), the reaction temperature is 55-58°C.

3. The preparation method according to claim 1, characterized in that In step (C): The reaction comprises sequentially performing a polymerization reaction and a deprotection reaction; The polymerization reaction temperature is 20-26°C; The deprotection reaction is carried out in the presence of a hydrogen bromide solution; the hydrogen bromide solution is a hydrogen bromide acetic acid solution; The temperature of the deprotection reaction is 20-26°C.

4. The preparation method according to claim 1, characterized in that In step (D): The reaction comprises sequentially performing a polymerization reaction and a deprotection reaction; The polymerization reaction temperature is 20-26°C; The deprotection reaction is carried out in the presence of a hydrogen bromide solution; the hydrogen bromide solution is a hydrogen bromide acetic acid solution; The temperature of the deprotection reaction is 20-26°C.

5. The preparation method according to claim 1, characterized in that The degree of polymerization x is 30~95, m1 is 35~85, m2 is 35~85, and m1=m2.

6. The preparation method according to claim 1, characterized in that In step E1: Dissolving the double-terminated polylysine polymer obtained in step (C) in water to obtain a solution with a concentration of 5% w / v to 20% w / v; The pH value is adjusted to 7.0-7.8; In step E2: Dissolving the double-terminated polyglutamic acid polymer obtained in step (D) in water to obtain a solution with a concentration of 5% w / v to 20% w / v; The pH value is adjusted to 7.0-7.8; In step E3: When the double-terminal polylysine polymer solution obtained in step E1 is mixed with the double-terminal polyglutamic acid polymer solution obtained in step E2, the molar ratio of amino groups in the double-terminal polylysine polymer to carboxyl groups in the double-terminal polyglutamic acid polymer is controlled to be 1:(0.8-1.2).

7. A polyamino acid hydrogel prepared by the preparation method according to any one of claims 1 to 6.

8. A method for preparing a hydrogel catheter, characterized in that: The following steps are involved: S1, dissolving the polymer in a solvent to obtain a spinning solution; Then, electrospinning is performed to obtain a polymer film; S2, forming the polymer film into a tube to obtain a catheter; S3, mixing the double-ended poly-lysine polymer solution and the double-ended poly-glutamic acid polymer solution into a gel in the catheter to obtain a hydrogel catheter; The double-terminated polylysine polymer solution is prepared by step E1 of the preparation method according to any one of claims 1 to 6, and the double-terminated polyglutamic acid polymer solution is prepared by step E2 of the preparation method according to any one of claims 1 to 6.

9. The preparation method according to claim 8, characterized in that In step S2, the electrospun membrane is formed into a tube by winding the membrane into a tube, comprising: cutting the polymer membrane obtained in step S1 into a rectangular shape, rolling the polymer membrane into a tube with a cylindrical mold as an axis, and then fixing the edges to obtain a tube; When the polymer film is cut into a rectangle, the parallel-oriented side is the length side and the vertical-oriented side is the width side; the parallel-oriented side corresponds to the catheter length and the vertical-oriented side is larger than the mold circumference; the fixing method is suturing.

10. A hydrogel catheter prepared by the preparation method according to any one of claims 8 to 9.

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