Biocompatible polyamide material, preparation method therefor ,and use thereof

Abstract

Disclosed are a biocompatible polyamide material, a preparation method therefor, and a use thereof. The biocompatible polyamide material is prepared using a dual catalyst-solvent chain-extension polymerization process, and all synthetic raw materials thereof are endogenous substances in the human body. The material can simulate natural protein materials, and possesses excellent biosafety, water solubility and biodegradability. During a process of cleavage and hydrolysis of amide bonds, the material can slowly release bioactive monomers thereof, to exercise unique biological functionality. The biocompatible polyamide material can be used in fields such as drug carriers, tissue fillers and cosmetics, and has broad application prospects. The preparation method is simple, low-cost, universal, and suitable for large-scale production.

Description

A biocompatible polyamide material and a preparation method and application thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of biomedical materials, in particular to a biocompatible polyamide material and a preparation method and application thereof. BACKGROUND

[0002] Polyamide (PA) is commonly known as nylon, which refers to a polymer containing amide bonds (-NHCO-) in the macromolecular chain. It is mainly divided into two categories according to its structure: aliphatic polyamide and aromatic polyamide. Among them, aliphatic polyamide is generally obtained by self-polymerization of lactam or amino acid, and polycondensation of aliphatic diamine and aliphatic diacid. Although polyamide is one of the most widely used high polymer materials, it has excellent comprehensive performance, but still has the disadvantages of non-biodegradability, poor solubility and poor dispersibility. The earliest soluble polyamide is mainly alcohol-soluble polyamide, which has serious organic emissions, and conflicts with the current trend of environmental protection and green chemistry technology, so it is very important to study water-soluble polyamide system. In addition, polypeptides and proteins are all macromolecular substances formed by the combination of amino acids through amide bonds, so water-soluble polyamides can be designed in structure and used as protein materials to imitate natural proteins.

[0003] Therefore, in recent decades, many research works have been devoted to improving the water solubility of polyamides. Strategies for improving the water solubility of polyamides include introducing flexible bonds, water-soluble chains and groups to the polyamide main chain, such as carboxyl groups, poly(alkylene oxide) segments, hydroxyethyl groups, etc.

[0004] The existing polyamide synthesis process needs to first add diacid and diamine into a solvent to form a salt, then concentrate the salt solution, pre-polymerize under high pressure to form an oligomer, and then decompress to normal pressure or micro-negative pressure for polycondensation reaction to form polyamide. The existing problems are that the polymerization time is long, side reactions are easy to occur, and the final polymer has poor color, wide molecular weight distribution and poor processability. Solution polycondensation method for synthesizing polyamide is to carry out polycondensation of reactants diacid / ester and diamine in solution, which requires that the selected solvent can dissolve polyamide and reaction monomers. Solution method for synthesizing polyamide has the advantages of low energy consumption, low reaction temperature and less reaction by-products. However, in order to synthesize macromolecular polyamide by this principle, it is necessary to improve the solubility of polyamide in the solvent, but the synthesized polyamide is a difficult-to-dissolve polymer after solidification due to the existence of a large number of hydrogen bonds in the molecule, and ordinary solvents cannot dissolve it, so the reaction conditions are harsh.

[0005] Chinese patent application CN107108881A discloses a method for producing a polycondensate powder dispersion, which uses a solvent to dissolve at least one diester and at least one diamine, produces a polyamide powder through the aminolysis of the ester in a one-step method, has the defects of fast reaction speed and many side reactions, and the solvent can only dissolve the diamine and the diester and / or the amino ester but not the polyamide formed during the polycondensation, also causes the polyamide molecules to be formed only through a one-step reaction and unable to be further chain-extended, and thus the molecular weight is difficult to be further improved.

[0006] Chinese patent CN102875803B discloses a water-soluble polyamide and a preparation method and application thereof, wherein the obtained polyamide product needs to be hydrolyzed under strong alkali conditions to obtain a water-soluble polyamide, the experimental conditions are harsh, the operation is complicated, and industrialization is not conducive. SUMMARY

[0007] The present application aims to overcome the defects of poor water solubility and difficult degradation of the existing polyamide materials, and provides a biocompatible polyamide material and a preparation method and application thereof. The biocompatible polyamide material is prepared by using a double catalysis-solvent chain extension polymerization process (DCEP). The raw materials of the biocompatible polyamide material are all endogenous substances in the human body, can simulate natural protein materials, and have excellent biological safety, water solubility and biodegradability.

[0008] The technical solution provided by the present application is as follows:

[0009] In the first aspect of the present application, a biocompatible polyamide is provided, which is polymerized from raw materials including esterification products of endogenous polyamines and endogenous polyacids, and a bifunctional catalyst is used in the polymerization; the bifunctional catalyst is a combination of an inorganic salt and an alkaline compound.

[0010] Further, the endogenous polyamine is any one of spermidine and spermine.

[0011] Further, the endogenous polyacid is selected from L-malic acid, succinic acid or alpha-ketoglutaric acid.

[0012] Further, the esterification product of the endogenous polyacid is a polybasic ester, in particular a diester, for example a diester formed by the endogenous polyacid and a lower alcohol (C1-C3), in particular malonic acid dimethyl ester, succinic acid dimethyl ester or alpha-ketoglutaric acid dimethyl ester.

[0013] Further, the inorganic salt is selected from chlorides of alkali metals and alkaline earth metals.

[0014] Further, the inorganic salt is any one of lithium chloride, calcium chloride, magnesium chloride.

[0015] Further, the basic compound is selected from one or more of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 1,8-diazabicycloundec-7-ene (DBU), sodium methoxide (NaOMe), triethylamine (TEA).

[0016] Further, the polyamide is a linear polymer.

[0017] In some embodiments of the present application, the polyamide comprises a structure selected from the group consisting of:

[0018] wherein n is the degree of polymerization, which is related to the molecular weight.

[0019] Further, the polyamide is prepared by the method of the second aspect of the present application.

[0020] In the second aspect of the present application, a method for preparing a biocompatible polyamide is provided, comprising the following steps:

[0021] (1) mixing an esterified endogenous polyacid and an endogenous polyamine, and subjecting them to bulk prepolymerization under solvent-free conditions to obtain a polyamide prepolymer;

[0022] (2) mixing the polyamide prepolymer, an organic solvent, and a dual-functional catalyst, and subjecting them to chain extension polymerization to obtain the biocompatible polyamide.

[0023] Further, the esterified endogenous polyacid and the endogenous polyamine in step (1) are as described in the first aspect of the present application.

[0024] Further, the molar ratio of the esterified endogenous polyacid to the endogenous polyamine in step (1) is 1:0.99-1.01, for example, 1:0.995-1.005, 1:0.999-1.001, or 1:1.

[0025] Further, the reaction in step (1) is carried out under an inert gas atmosphere; the inert gas is any one of nitrogen, argon, helium, neon, krypton, xenon, or carbon dioxide, for example, nitrogen.

[0026] Further, the reaction in step (1) is carried out under stirring (stirring until the system solidifies).

[0027] Further, the reaction temperature in step (1) is 20-30°C (for example, 20, 25, or 30°C).

[0028] Further, the reaction time in step (1) is 30 min-5 h (such as 30 min, 1 h, 2 h, 3 h, 4 h, 5 h).

[0029] The present application uses specific endogenous polyamines, such as spermine or spermidine, and esters of endogenous polyacids, such as dimethyl malate, dimethyl succinate or dimethyl alpha-ketoglutarate, etc., as raw materials. These endogenous polyamines and endogenous polyacids are normal active ingredients in the body and have good biocompatibility. The reaction activity of the polyamines and esters used in the present application is relatively high. The presence of a secondary amine group in spermine or spermidine makes the reaction system alkaline, which is easy to cause decarboxylation during the reaction process. Therefore, it is difficult to obtain high molecular weight polyamide polymers by conventional melt polycondensation. Based on this, the present application innovatively proposes a two-step polymerization process of bulk prepolymerization under solvent-free conditions and chain extension polymerization under solvent conditions, thereby effectively solving the problems encountered by active molecules in the polymerization process.

[0030] Further, the mixing of step (2) is specifically mixing the organic solvent with the inorganic salt in the bifunctional catalyst, then adding the polyamide prepolymer, stirring and dissolving, and then adding the basic compound in the bifunctional catalyst and mixing uniformly.

[0031] Further, the inorganic salt in step (2) is selected from chlorides of alkali metals and alkaline earth metals, in particular any one of lithium chloride, calcium chloride, magnesium chloride, and preferably lithium chloride.

[0032] Further, the basic compound in step (2) is selected from one or more of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 1,8-diazabicycloundec-7-ene (DBU), sodium methoxide (NaOMe), and triethylamine (TEA), and preferably TBD.

[0033] Further, the organic solvent in step (2) is any one of N,N-dimethylacetamide (DMAc) and N-methyl pyrrolidone (NMP).

[0034] Further, in the bifunctional catalyst, the mass ratio of the inorganic salt to the basic compound is 1:0.05-3 (such as 1:0.08, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.8, 1:0.9, 1:1, 1:1.5, 1:2, 1:2.5, 1:2.7, 1:2.8, 1:3).

[0035] Further, the mass ratio of the inorganic salt to the polyamide prepolymer is 1:2-15 (such as 1:3, 1:5, 1:6, 1:7, 1:8, 1:10, 1:12, 1:14, 1:15), such as 1:5-10.

[0036] Further, the mixing and polymerization reaction in step (2) is carried out under an inert gas atmosphere; the inert gas is any one of nitrogen, argon, helium, neon, krypton, xenon or carbon dioxide, such as nitrogen.

[0037] Further, the mixing and chain extension polymerization reaction in step (2) is carried out under stirring.

[0038] Further, the polymerization reaction temperature in step (2) is 40-160°C (such as 40, 50, 60, 70, 80, 85, 90, 95, 100, 105, 120, 140, 160°C), for example, 60-140°C.

[0039] Further, the polymerization reaction time in step (2) is 1-24h (such as 1, 2, 3, 4, 5, 6, 8, 10, 12, 16, 18, 24h), for example, 3-18h.

[0040] The present application uses a bifunctional catalyst for chain extension polymerization of polyamide prepolymer, by first mixing inorganic salt in the bifunctional catalyst with organic solvent for dissolving polyamide prepolymer, then adding basic compound to catalyze polymerization reaction. Among them, based on safety and catalytic effect, lithium chloride and calcium chloride, magnesium chloride of alkali metal and alkaline earth metal are selected as inorganic salt catalyst, chloride ion is a trace element existing in human body, which has obvious safety advantage compared with bromine and iodine, and the nucleophilic ability of chloride ion is strong, which is beneficial to nucleophilic attack reaction; and in the selection of cation, Li + is the simplest and most representative metal ion of alkali metal, its high charge density and stable helium type double electron layer make Li + easily polarize other molecules or ions, itself is not easy to be polarized, its properties are between metal and non-metal, which can effectively combine with carbonyl in amide and destroy intermolecular hydrogen bond; in addition, based on the diagonal principle in periodic table, Mg 2+ has similar properties with Li + , and Ca 2+ is homologous with Mg 2+ , and also has the effect of effectively combining with carbonyl in amide and destroying intermolecular hydrogen bond; at the same time, lithium and calcium, magnesium are trace elements existing in human body, which have high safety, therefore we select LiCl, CaCl2 and MgCl2 as inorganic salt catalyst, and basic compound catalyst as bifunctional catalyst to catalyze further chain extension polymerization of polyamide prepolymer, and obtain high molecular weight polyamide.

[0041] In the chain extension polymerization, the inorganic salt catalyst added first, on the one hand, due to its cation (such as Li + , Ca2+ Mg 2+ ) can open the hydrogen bond in the polyamide prepolymer group, and form a complex with the amide group which is stronger than the hydrogen bond, thus releasing the N-H bond, and then form a hydrogen bond with the anion (such as Cl - ) in the inorganic salt, to obtain an intermediate with a complex structure, so that the polyamide prepolymer can be fully dissolved; on the other hand, after the introduction of the basic compound catalyst, with the further progress of the aminolysis of the ester, in the chain extension polymerization process, the amine group in the polyamide prepolymer will have an intermolecular nucleophilic attack on the ester carbonyl group of the polyamide prepolymer under the catalysis of the basic compound, and the free Cl - in the inorganic salt catalyst will form a hydrogen bond with the amine group in the polyamide prepolymer, thus enhancing the electronegativity of the amine group, which can further promote the occurrence of the nucleophilic reaction, so that the reaction proceeds in the required direction, and the molecular weight of the final product is increased. When the molecular weight is further increased, the hydrogen bond formed will also be further increased, so that the ion pair interaction is reduced, thereby causing the chain-extended polyamide to precipitate out of the solution. Therefore, when the inorganic salt is added to the system to form a new ion pair, the chain-extended polyamide can be dissolved in the system again. However, due to the reduction of the proportion of primary amine groups in the terminal groups of the chain-extended polyamide, a small amount of active end groups is difficult to further perform chain extension polymerization reaction, so that the chain extension effect is limited after re-dissolution.

[0042] In some embodiments of the present application, step (1) comprises: adding the esterified product of the endogenous polyacid and the endogenous polyamine into a reaction container, stirring until the system solidifies in an inert gas atmosphere, to obtain a polyamide prepolymer.

[0043] In some embodiments of the present application, step (2) comprises: mixing the organic solvent with the inorganic salt in the bifunctional catalyst, then adding the polyamide prepolymer, heating and stirring until the polyamide prepolymer is completely dissolved in an inert gas atmosphere, adding the basic compound in the bifunctional catalyst, and continuing to heat and stir the reaction.

[0044] Further, the preparation method further comprises a step of washing the reaction product obtained in step (2); further, the solvent used for washing can be anhydrous ethanol; further, the washing can be one or more times, for example, 3 times.

[0045] Further, the preparation method further comprises a step of drying the reaction product obtained in step (2) or the product after washing; further, the drying can be performed at 35-50°C (for example, 35, 40, 45, or 50°C) under vacuum.

[0046] In the third aspect of the present application, the polyamide prepared by the method of the second aspect is used in the preparation of a drug carrier, a tissue filler, etc.

[0047] Further, the tissue filler is an injection, which can be used for medical cosmetical filling (such as nasolabial fold, forehead, temple, chin, hand, etc.) and anti-aging, etc., and can further comprise one or more cosmetically acceptable excipients.

[0048] In a fourth aspect of the present application, the use of the polyamide of the first aspect or the polyamide prepared by the method of the second aspect in the preparation of a cosmetic is provided.

[0049] Further, the cosmetic can further comprise one or more cosmetically acceptable excipients.

[0050] Further, the cosmetic can be a cosmetic for the face, such as serum, mask, gel, cream, etc.

[0051] Further, the cosmetic can be a cosmetic for other parts of the body other than the face, such as neck cream, body milk, etc.

[0052] Further, the polyamide is prepared as described in the second aspect of the present application.

[0053] In a fifth aspect of the present application, the use of the polyamide of the first aspect or the polyamide prepared by the method of the second aspect in medical cosmetical filling (such as nasolabial fold, forehead, temple, chin, hand, etc.) is provided.

[0054] In a sixth aspect of the present application, a tissue filler comprising the polyamide of the first aspect or the polyamide prepared by the method of the second aspect is provided.

[0055] Further, the tissue filler is an injection, which can be used for medical cosmetical filling (such as nasolabial fold, forehead, temple, chin, hand, etc.) and anti-aging, etc., and can further comprise one or more cosmetically acceptable excipients.

[0056] In a seventh aspect of the present application, a cosmetic comprising the polyamide of the first aspect or the polyamide prepared by the method of the second aspect is provided.

[0057] Further, the cosmetic can further comprise one or more cosmetically acceptable excipients.

[0058] Further, the cosmetic can be a cosmetic for the face, such as serum, mask, gel, cream, etc.

[0059] Further, the cosmetic can be a cosmetic for other parts of the body other than the face, such as neck cream, body milk, etc.

[0060] In an eighth aspect of the present application, there is provided a method of preparing a tissue filler or cosmetic (as described in the third, fourth, sixth, seventh, and eighth aspects of the present application), comprising the step of using the polyamide of the first aspect or the polyamide prepared by the method of the second aspect.

[0061] In a ninth aspect of the present application, there is provided a method of medical cosmetic filling, comprising the step of administering the polyamide of the first aspect or the polyamide prepared by the method of the second aspect.

[0062] Further, the administration route is injection.

[0063] Further, the administration site is nasolabial groove, forehead, temple, chin, hand, etc.

[0064] The present application has the following beneficial effects:

[0065] (1) The present application uses specific endogenous polyamines, such as spermine or spermidine, and esters of endogenous polyacids, such as dimethyl malonate, dimethyl succinate, or dimethyl α-ketoglutarate, as raw materials. First, bulk pre-polymerization is carried out under solvent-free conditions, and the primary amine in the endogenous polyamine is involved in the reaction to form a pre-polymer. Subsequently, chain extension polymerization is carried out under solvent conditions. By controlling the ratio of raw materials, the secondary amine in the endogenous polyamine does not participate in the reaction in the chain extension polymerization stage, forming a linear polymer. Thus, the prepared polyamide is water-soluble, has good biocompatibility, is extremely safe, and has certain biological functionality.

[0066] (2) The present application uses a bifunctional catalyst for the chain extension polymerization of the polyamide pre-polymer. In the chain extension polymerization, the inorganic salt catalyst is added first. On the one hand, the cation (such as Li + , Ca 2+ , Mg 2+ ) can open the hydrogen bond in the polyamide pre-polymer group and produce complexation with the amide group that is stronger than hydrogen bonding, thereby releasing the N-H bond and forming a hydrogen bond with the anion (such as Cl - ) in the inorganic salt, obtaining an intermediate with a complex structure, so that the polyamide pre-polymer can be fully dissolved. On the other hand, after the introduction of the basic compound catalyst, the amine group in the polyamide pre-polymer will undergo intermolecular nucleophilic attack on the ester carbonyl group of the polyamide pre-polymer under the catalysis of the basic compound in the chain extension polymerization process. The free Cl -The amine group in the polyamide prepolymer can form hydrogen bonds, thereby enhancing the electronegativity of the amine group, further promoting the occurrence of nucleophilic reaction, making the reaction proceed in the required direction, and increasing the molecular weight of the final product. When the molecular weight is further increased, the formed hydrogen bonds are further increased, which reduces the ion pair effect, thereby causing the chain-extended polyamide to precipitate from the solution. Therefore, when inorganic salts are added to the system to form new ion pairs, the chain-extended polyamide can be dissolved in the system again. However, due to the reduced proportion of primary amine groups in the chain-extended polyamide, a small amount of active end groups is difficult to further perform chain extension polymerization, and therefore the chain extension effect is limited after being dissolved again.

[0067] (3) The synthetic method applied in the present application is simple, low in cost, universal, and easy to scale up. The obtained biocompatible polyamide can simulate natural protein components, and can be used as a makeup product and a care product for the face and body when used externally, and can be used as a tissue filling water-light, a drug carrier, and the like when used for injection, and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0068] FIG. 1 shows the comparison photos of the biocompatible polyamide obtained in Example 2 of the present application before (left) and after (right) being dissolved in purified water, with a concentration of 100 mg / ml.

[0069] FIG. 2 shows the HNMR chart of the biocompatible polyamide obtained in Example 2 of the present application. 1

[0070] FIG. 3 shows the infrared spectrum of the biocompatible polyamide obtained in Example 2 of the present application.

[0071] FIG. 4 shows the comparison photos of the polyamide obtained in Comparative Example 3 of the present application before (left) and after (right) being dissolved in purified water, with a concentration of 100 mg / ml.

[0072] FIG. 5 shows the test results of the effect of the biocompatible polyamide obtained in Example 2 of the present application on cell proliferation and the control blank test results. DETAILED DESCRIPTION

[0073] Unless otherwise defined, all scientific and technical terms used in the present application have the same meanings as commonly understood by one of ordinary skill in the art to which the present application pertains.

[0074] In the present application, the term "prepolymer" refers to both oligomers and / or polyamides obtained by polycondensation.

[0075] In the present application, the term "polyamide" refers to the condensation product of a polyamine and a dibasic ester, and as a general rule, means any polymer formed by units connected to each other by amide groups. ​

[0076] In the present application, the term "monomer" refers to a repeating unit of a prepolymer or a polyamide.

[0077] In the present application, the term "vial" refers to a borosilicate glass or soda-lime glass tube (molded) injection bottle, a small bottle with a rubber stopper and an aluminum-plastic combined cap seal. It is named after the early penicillin, which is often used to contain it. Vial.

[0078] In the present application, the raw materials and reagents used are commercially available.

[0079] The technical solutions of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0080] Synthesis example 1: preparation of polyamide prepolymer 1 with dimethyl malate and spermidine

[0081] Take 5.59g dimethyl malate (34.5mmol) and 5.01g spermidine (34.5mmol) in a round-bottom flask, vacuum to remove air in the bottle, and introduce nitrogen. Under the nitrogen atmosphere, stir the reaction at 25℃ for 30min, until the system solidifies, to obtain polyamide prepolymer 1.

[0082] Synthesis example 2: preparation of polyamide prepolymer 2 with dimethyl succinate and spermidine

[0083] Take 1.46g dimethyl succinate (10mmol) and 1.45g spermidine (10mmol) in a round-bottom flask, vacuum to remove air in the bottle, and introduce nitrogen. Under the nitrogen atmosphere, stir the reaction at 20℃ for 4h, until the system solidifies, to obtain polyamide prepolymer 2.

[0084] Synthesis example 3: preparation of polyamide prepolymer 3 with dimethyl ketoglutarate and spermidine

[0085] Take 1.74g dimethyl ketoglutarate (10mmol) and 1.45g spermidine (10mmol) in a round-bottom flask, vacuum to remove air in the bottle, and introduce nitrogen. Under the nitrogen atmosphere, stir the reaction at 30℃ for 1h, until the system solidifies, to obtain polyamide prepolymer 3.

[0086] Synthesis example 4: preparation of polyamide prepolymer 4 with dimethyl malate and spermine

[0087] Take 1.62 g of dimethyl malonate (10 mmol) and 2.02 g of spermine (10 mmol) in a round-bottom flask, vacuum to remove air in the flask, and introduce nitrogen. Stir the reaction at 25°C for 30 min under nitrogen atmosphere until the system solidifies to obtain polyamide prepolymer 4.

[0088] Synthesis Example 5 Preparation of polyamide prepolymer 5 from dimethyl malonate and spermidine

[0089] Take 1.62 g of dimethyl malonate (10 mmol) and 2.02 g of spermine (10 mmol) in a round-bottom flask, vacuum to remove air in the flask, and introduce nitrogen. Stir the reaction at 25°C for 30 min under nitrogen atmosphere until the system solidifies to obtain polyamide prepolymer 4.

[0090] Example 1 Water-soluble polyamide prepared from dimethyl malonate and spermidine

[0091] Weigh 1.30 g of prepolymer 1 (5 mmol), then dissolve 0.17 g of inorganic salt lithium chloride in 3 ml of organic solvent DMAc to prepare a mixed solution. Add prepolymer 1 to the mixed solution and place it in a round-bottom flask. Vacuum to remove air in the flask, introduce nitrogen, and then heat to 100°C under nitrogen atmosphere. Stir for 30 min until the prepolymer is completely dissolved. Then add 0.035 g of basic compound TBD (0.25 mmol) to the reaction system and stir at 80°C for 8 h. After the reaction is completed, wash the product with anhydrous ethanol 3 times and then place it in a 40°C vacuum drying oven to dry to obtain polyamide product 1.

[0092] Example 2 Water-soluble polyamide prepared from dimethyl malonate and spermidine

[0093] Weigh 1.30 g of prepolymer 1 (5 mmol), then dissolve 0.17 g of inorganic salt lithium chloride in 3 ml of organic solvent DMAc to prepare a mixed solution. Add prepolymer 1 to the mixed solution and place it in a round-bottom flask. Vacuum to remove air in the flask, introduce nitrogen, and then heat to 100°C under nitrogen atmosphere. Stir for 30 min until the prepolymer is completely dissolved. Then add 0.035 g of basic compound TBD (0.25 mmol) to the reaction system and stir at 80°C for 8 h. After the reaction is completed, wash the product with anhydrous ethanol 3 times and then place it in a 40°C vacuum drying oven to dry to obtain polyamide product 1.

[0094] The polyamide product 2 before and after being dissolved in purified water is shown in Figure 1. As can be seen from the left graph of Figure 1, the dried polyamide is a white powder, and the polyamide can be dissolved in purified water to obtain the colorless and transparent solution (concentration is 100 mg / mL) shown in the right graph, indicating that the prepared polyamide can be completely dissolved at high concentration and has complete water solubility. In addition, the polyamide product 2 was respectively dissolved in purified water and 0.9% sodium chloride solution, and the results are shown in Figure 2.1 HNMR, infrared spectrum analysis of product 2. From the HNMR chart of Figure 2, it can be seen that there is an absorption peak of methylene adjacent to the secondary amine group at 2.45 ppm, and an absorption peak of methylene adjacent to the N atom in the characteristic group -CO-NH- of the synthetic polyamide in the range of 3.0-3.4 ppm, indicating that linear polyamide is formed; from the infrared spectrum chart of Figure 3, it can also be seen that there is an absorption peak of the secondary amine (-NH-) at 3301 cm 1 From the HNMR chart, it can be seen that there is an absorption peak of methylene adjacent to the secondary amine group at 2.45 ppm, and an absorption peak of methylene adjacent to the N atom in the characteristic group -CO-NH- of the synthetic polyamide in the range of 3.0-3.4 ppm, indicating that linear polyamide is formed; from the infrared spectrum chart of Figure 3, it can also be seen that there is an absorption peak of the secondary amine (-NH-) at 3301 cm -1 From the HNMR chart, it can be seen that there is an absorption peak of methylene adjacent to the secondary amine group at 2.45 ppm, and an absorption peak of methylene adjacent to the N atom in the characteristic group -CO-NH- of the synthetic polyamide in the range of 3.0-3.4 ppm, indicating that linear polyamide is formed; from the infrared spectrum chart of Figure 3, it can also be seen that there is an absorption peak of the secondary amine (-NH-) at 3301 cm

[0095] Example 3 Water-soluble polyamide prepared from dimethyl malonate and spermidine

[0096] 1.30 g of prepolymer 1 (5 mmol) was weighed, then 0.17 g of inorganic salt lithium chloride was dissolved in 3 ml of organic solvent DMAc to prepare a mixed solution, the prepolymer 1 was added to the mixed solution and placed in a round-bottom flask, the air in the flask was exhausted by vacuum, then nitrogen was introduced, and the temperature was raised to 100°C under nitrogen atmosphere, and stirred for 30 min until the prepolymer was completely dissolved. Then 0.152 g of basic compound DBU (1 mmol) was added to the reaction system, and stirred at 100°C for 4 h. After the reaction was completed, the product was washed with anhydrous ethanol for 3 times, and then placed in a vacuum drying oven at 40°C to dry to obtain the polyamide product 3.

[0097] Example 4 Water-soluble polyamide prepared from dimethyl malonate and spermidine

[0098] 1.30 g of prepolymer 1 (5 mmol) was weighed, then 0.17 g of inorganic salt lithium chloride was dissolved in 3 ml of organic solvent DMAc to prepare a mixed solution, the prepolymer 1 was added to the mixed solution and placed in a round-bottom flask, the air in the flask was exhausted by vacuum, then nitrogen was introduced, and the temperature was raised to 100°C under nitrogen atmosphere, and stirred for 30 min until the prepolymer was completely dissolved. Then 0.152 g of basic compound DBU (1 mmol) was added to the reaction system, and stirred at 100°C for 4 h. After the reaction was completed, the product was washed with anhydrous ethanol for 3 times, and then placed in a vacuum drying oven at 40°C to dry to obtain the polyamide product 3.

[0099] Example 5 Water-soluble polyamide prepared from dimethyl malonate and spermidine

[0100] Take 1.44 g of prepolymer 4 (5 mmol), then take 0.19 g of inorganic salt magnesium chloride and dissolve in 3.4 ml of organic solvent DMAc to prepare a mixed solution, add prepolymer 4 to the mixed solution and place it in a round-bottom flask, vacuum to remove the air in the bottle, after purging with nitrogen, heat to 100°C under nitrogen atmosphere, stir for 30 min until the prepolymer is completely dissolved. Then take 0.506 g of basic compound triethylamine (5 mmol) and add it to the reaction system, stir at 60°C for 18 h. After the reaction is completed, the product is collected after washing with anhydrous ethanol 3 times, and then dried in a vacuum drying oven at 40°C to obtain polyamide product 5.

[0101] Example 6 Water-soluble polyamide prepared from dimethyl succinate and spermidine

[0102] Take 1.22 g of prepolymer 2 (5 mmol), then take 0.16 g of inorganic salt lithium chloride and dissolve in 2.9 ml of organic solvent DMAc to prepare a mixed solution, add prepolymer 2 to the mixed solution and place it in a round-bottom flask, vacuum to remove the air in the bottle, after purging with nitrogen, heat to 100°C under nitrogen atmosphere, stir until the prepolymer is completely dissolved. Then take 0.069 g of basic compound TBD (0.5 mmol) and add it to the reaction system, continue to stir at 140°C for 3 h. After the reaction is completed, the product is collected after washing with anhydrous ethanol 3 times, and then dried in a vacuum drying oven at 40°C to obtain polyamide product 6.

[0103] Example 7 Water-soluble polyamide prepared from dimethyl ketopentandioate and spermidine

[0104] Take 1.36 g of prepolymer 3 (5 mmol), then take 0.18 g of inorganic salt lithium chloride and dissolve in 3.2 ml of organic solvent DMAc to prepare a mixed solution, add prepolymer 3 to the mixed solution and place it in a round-bottom flask, vacuum to remove the air in the bottle, after purging with nitrogen, heat to 100°C under nitrogen atmosphere, stir until the prepolymer is completely dissolved. Then take 0.069 g of basic compound TBD (0.5 mmol) and add it to the reaction system, continue to stir at 100°C for 4 h. After the reaction is completed, the product is collected after washing with anhydrous ethanol 3 times, and then dried in a vacuum drying oven at 40°C to obtain polyamide product 7.

[0105] Example 8 Water-soluble polyamide prepared from dimethyl ketopentandioate and spermidine

[0106] Take 1.36 g of prepolymer 3 (5 mmol), then take 0.18 g of inorganic salt lithium chloride and dissolve in 3.2 ml of organic solvent DMAc to prepare a mixed solution, add prepolymer 3 to the mixed solution and place it in a round-bottom flask, vacuum to remove air in the bottle, and then introduce nitrogen. After heating to 100℃ under nitrogen atmosphere, stir until the prepolymer is completely dissolved. Then take 0.069 g of basic compound TBD (0.5 mmol) and add it to the reaction system. Continue stirring at 100℃ for 4h to precipitate the polyamide product. Then take 0.09 g of inorganic salt lithium chloride and add it to the polymerization system. Heat and stir at 100℃ until the reaction system becomes clear. Continue polymerization for 4h and then stop the reaction. Wash with anhydrous ethanol 3 times, collect the product, and dry in a 40℃ vacuum drying oven to obtain polyamide product 8.

[0107] Example 1 Preparation of polyamide from dimethyl malonate and spermidine without solvent

[0108] Take 1.30 g of prepolymer 1 (5 mmol) and do not add solvent. Vacuum to remove air in the bottle, introduce nitrogen, then add 0.035 g of basic compound TBD (0.25 mmol), heat to 100℃ under nitrogen atmosphere, and react for 4h. It can be found that as the reaction proceeds, the reactant gradually changes from white to yellow and finally black, indicating that the product has been carbonized. This is mainly due to the fact that the spermidine and malonic acid used in the present invention are small molecule active monomers, which are not resistant to high temperature. This is significantly different from the non-active raw materials such as hexanediamine, ethylenediamine and adipic acid used in the existing invention, so it cannot be used for melt polymerization, but only for chain extension polymerization by solution dissolution.

[0109] Example 2 Preparation of polyamide from dimethyl malonate and spermidine

[0110] Take 1.30 g of prepolymer 1 (5 mmol) and place it in a round-bottom flask. Add 3 ml of DMAc to the round-bottom flask, vacuum to remove air in the bottle, introduce nitrogen, and then heat to 100℃ under nitrogen atmosphere. Stir for 30 min until the prepolymer is completely dissolved. Then take 0.035 g of catalyst TBD (0.25 mmol) and add it to the reaction system. Stir at 100℃ for 4h. After the reaction is completed, wash with anhydrous ethanol 3 times, collect the product, and dry in a 40℃ vacuum drying oven to obtain polyamide product 9.

[0111] Example 3 Preparation of polyamide from dimethyl malonate and spermidine

[0112] Take 1.30 g of prepolymer 5 (5 mmol), weigh 0.17 g of inorganic salt lithium chloride dissolved in 3 ml of organic solvent DMAc to prepare a mixed solution, add prepolymer 5 to the mixed solution and place it in a round-bottom flask, vacuum to remove air in the bottle, after nitrogen is introduced, heat to 100°C under nitrogen atmosphere, stir for 30 min until the prepolymer is completely dissolved. Then take 0.035 g of basic compound TBD (0.25 mmol) and add it to the reaction system, stir at 100°C for 4 h, after the reaction is completed, wash with anhydrous ethanol 3 times to collect the product, and dry in a 40°C vacuum drying oven to obtain the polyamide product 10.

[0113] The polyamide product 10 before and after being dissolved in purified water is shown in Figure 4. The final polymer is red-brown (see Figure 4 left), and after adding purified water, the polymer is poorly water-soluble and shows a gel-like water absorption (see Figure 4 right), indicating that when the ester content is too high, the resulting polyamide polymer is nonlinear, and therefore difficult to dissolve.

[0114] Performance test

[0115] In order to reflect the differences in the properties of the polyamides obtained in the above examples and comparative examples, the molecular weight, relative viscosity, degradation performance and cell safety of the polyamide samples obtained in the above examples and comparative examples were detected. The relative viscosity was measured by Ubbelohde viscometer method; the molecular weight was measured by GPC; the degradation performance was measured by Ubbelohde viscometer method; and the cell safety was measured by cell proliferation and cytotoxicity kit (Cell Counting Kit-8, CCK-8).

[0116] Performance example 1: polyamide molecular weight and relative viscosity test

[0117] The polyamide samples of examples 1-8 and comparative example 2 were measured for molecular weight by water-phase GPC, and the test results are shown in Table 1. The test process is as follows:

[0118] (1) Diluent: consistent with the mobile phase;

[0119] (2) Test sample solution (2 mg / ml): weigh 20 mg of sample into a conical flask, add 10 ml of diluent, and dissolve by shaking;

[0120] (3) Chromatographic column: UP-SW3000-LS;

[0121] (4) Mobile phase: 0.2M sodium lactate, pH adjusted to 4.0 with 10% trichloroacetic acid;

[0122] (5) Flow rate: 0.2 ml / min; injection volume: 50 μL; column temperature: 25°C; detector temperature: 25°C;

[0123] (6) Run time: 45 min (differential 41 min).

[0124] The relative viscosity of the polyamide samples of Examples 1-8 and Comparative Example 2 was tested by using an Ubbelohde viscometer, and the test results are shown in Table 1. The specific test procedure is as follows: 30 mg of sample was weighed into a 40 ml Schlenk flask, 30 ml of phosphate buffer at pH 7.4 was added to prepare a 1 mg / ml polyamide solution, and the relative viscosity of the polyamide solution at 25°C was tested.

[0125] Table 1 Test results of polyamide molecular weight and relative viscosity

[0126] As can be seen from Table 1, by using the esterification product of the small molecule endogenous polyamine and endogenous polyacid with high activity as raw material, the polyamides of Examples 1-8 prepared finally have high molecular weight. In addition, it can also be seen from the table that the molecular weight of Example 2 is absolutely greatly improved (increased by 563.6%) compared with Comparative Example 2, which is mainly due to the use of a bifunctional catalyst for chain extension polymerization of the polyamide prepolymer in Example 2. After the lithium chloride in the bifunctional catalyst is mixed and dissolved with the organic solvent, Li + can open the hydrogen bond in the cured polyamide group and produce complexation with the amide group that is stronger than hydrogen bonding, thereby releasing the N-H bond, and then Cl - in the inorganic salt forms a hydrogen bond to obtain an intermediate with a complex structure, so that the polyamide prepolymer can be fully dissolved; after the introduction of the basic compound catalyst, the amine group in the polyamide prepolymer will undergo a nucleophilic attack reaction on the ester carbonyl group of the polyamide prepolymer under the catalysis of the basic compound, and the free Cl - in the inorganic salt catalyst will form a hydrogen bond with the amine group in the polyamide prepolymer, thereby enhancing the electronegativity of the amine group, which can further promote the occurrence of nucleophilic reaction, so that the reaction proceeds in the required direction, and the molecular weight of the final product is greatly improved. In Comparative Example 2, since no inorganic salt is added during the polycondensation stage, the polyamide is difficult to dissolve, and therefore the corresponding reaction efficiency is low, and the molecular weight of the final polymer is also low.

[0127] Further, in Example 8, by continuing to add the inorganic salt LiCl, the polyamide product that has been precipitated can be dissolved again, but its molecular weight is only partially improved (increased by 0.54%) compared with Example 7, which is mainly due to the fact that the degree of polymerization of the polyamide product is close to the end point, and the content of the terminal group ester is very low, so the probability of polymerization after continued dissolution is low, and therefore the increase in the molecular weight of the product is very limited.

[0128] In addition, the relative viscosity of the polymer is a means for expressing the relative molecular weight of the soluble polymer. As can be seen from Table 1, the relative viscosity of the polymer increases with the increase of the molecular weight, and the relative viscosity of the 1 mg / ml polymer solution is within 1.5-3 dL / g, indicating that the relative viscosity is moderate, and it is also suitable for further processing into other medical materials in the later stage, and has a wide range of applications.

[0129] Performance Example 2: Determination of in vitro degradation performance of the polyamide

[0130] 10 mg of the polyamide sample powder of Example 2 and Comparative Example 2 was respectively placed in a 10 ml vial, 10 ml of pH 7.4 phosphate buffer was added to each vial to prepare a 1 mg / ml polyamide solution, the bottle opening was sealed and placed in a constant temperature shaker at 37°C, the relative viscosity of the sample was tested every three days using an Ubbelohde viscometer, and the degradation of the polyamide in the buffer was monitored according to the change of the relative viscosity, and the change results of the relative viscosity are shown in Table 2.

[0131] Table 2 Change results of the relative viscosity of the polyamide in the degradation process of Example 2 and Comparative Example 2

[0132] As can be seen from Table 2, the polyamide material prepared by the two-step polymerization process of bulk prepolymerization under solvent-free conditions and chain extension polymerization in a solvent according to the present application is not only a water-soluble material, but also a biocompatible material that can be completely degraded in water. The data in Table 2 show that the polyamide samples of Example 2 and Comparative Example 2 both exhibit a uniform hydrolysis process. The relative viscosity of the sample of Comparative Example 2 with a molecular weight of 6.51 kDa does not change after the 6th day and remains unchanged, indicating that it reaches degradation equilibrium around 6 days. The relative viscosity of Example 2 with a molecular weight of 43.2 kDa is still 0.85 dL / g at the 15th day of degradation, which is significantly higher than that of Comparative Example 2 before degradation (0.39 dL / g), indicating that the degradation period of the polyamide of Example 2 is much better than that of Comparative Example 2.

[0133] Performance Example 3: Effect of the polyamide on cell proliferation

[0134] The polyamide sample of Example 2 was taken to test its effect on cell proliferation, and a blank control test was performed for comparison.

[0135] The specific operation of the cell proliferation test is as follows: L-929 cells were planted in a cell culture medium, 1% penicillin-streptomycin solution and 10% fetal bovine serum solution were added. The L-929 cells were incubated in a humidified cell culture incubator containing 5% carbon dioxide at 37°C for 2 days for standby. 1 mL of trypsin solution containing 0.1% EDTA was added to the L-929 cell culture medium, and the concentration of the L-929 cells was adjusted to 1x104 L929 cells were seeded in 96-well plates at 100 μL solution per well. 10 mg and 20 mg of the polyamide obtained in Example 2 were weighed into sterile centrifuge tubes, sterilized under UV light, and then 1 ml of culture medium was added to each centrifuge tube to dissolve the polyamide, to prepare a 10 mg / ml and 20 mg / ml polyamide concentration medium solution. After filtering the solution again using a 0.2 μm filter membrane to sterilize, it was added to the well plate and placed in a cell culture incubator to promote cell growth.

[0136] The polyamide cell proliferation rate was determined by a cell proliferation and cytotoxicity kit (Cell Counting Kit-8, CCK-8). After 24 h of culture, 100 μL of CCK-8 reagent was added to each well and placed in the incubator for 1 h of incubation. Then the absorbance of the solution at 450 nm was detected using a microplate reader. The cell survival rate was calculated according to the following formula:

[0137] Cell proliferation rate (%) = (As / Ac) x 100%;

[0138] wherein As is the absorbance of the sample solution at 450 nm, and Ac is the absorbance of the blank control at 450 nm.

[0139] The cell proliferation results are shown in Figure 5. As can be seen from the figure, the water-soluble polyamide material of the present application has a 24 h cell survival rate of 102% and 106% respectively when the polymer concentration is as high as 10 mg / ml and 20 mg / ml, indicating that the ester of the selected endogenous polyamine and endogenous polyacid is used as the raw material to obtain a water-soluble polyamide material with good biocompatibility. Compared with the linear polyamide material obtained by polymerizing spermidine and sebacoyl dichloride in the prior art (Int. J. Mol. Sci. 2024, 25(5), 2576), the survival rate of fibroblasts (i.e. L-929 cells) is below 80% at a polyamide concentration of 2 mg / ml, which is much lower than the 106% cell survival rate at a polyamide concentration of 20 mg / ml in the present application. The reason may be that the acyl chloride in the literature is a potential genotoxic impurity, which has genetic toxicity and carcinogenicity, so the prepared polyamide material has strong toxicity and poor biocompatibility. The monomers used in the water-soluble polyamide of the present application are all biologically active components present in the human body, and the monomers and polymerization products are all non-cytotoxic, which is a safe biologically active material.

[0140] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0141] The foregoing examples and methods described in the present application can vary based on the ability, experience, and preference of the person skilled in the art.

[0142] The fact that the steps of a method are listed in a certain order in the present application does not constitute any limitation on the order of the steps of the method.

Claims

1. A biocompatible polyamide, which is polymerized from raw materials comprising an ester of an endogenous polyamine and an endogenous polyacid; wherein a bifunctional catalyst is used in the polymerization, the bifunctional catalyst being a combination of an inorganic salt and a basic compound.

2. The biocompatible polyamide of claim 1, wherein, The endogenous polyamine is any one of spermidine and spermine; and / or the ester of the endogenous polyacid is a diester, in particular dimethyl malonate, dimethyl succinate, dimethyl α-ketoglutarate.

3. The biocompatible polyamide of claim 1, wherein, The inorganic salt is selected from chlorides of alkali metals and alkaline earth metals; preferably any one of lithium chloride, calcium chloride, magnesium chloride; Preferably, the basic compound is selected from one or more of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 1,8-diazabicycloundec-7-ene (DBU), sodium methoxide (NaOMe), triethylamine (TEA).

4. The biocompatible polyamide according to any one of claims 1 to 3, wherein The polyamide is a linear polymer. 5.A method for preparing the biocompatible polyamide of any one of claims 1-4, comprising the following steps: (1) mixing the ester of the endogenous polyacid and the endogenous polyamine, and subjecting them to bulk prepolymerization under solvent-free conditions to obtain a polyamide prepolymer; (2) mixing the polyamide prepolymer, an organic solvent and the bifunctional catalyst, and subjecting them to chain extension polymerization to obtain the biocompatible polyamide.

6. The production method according to claim 5, wherein In step (1), the molar ratio of the ester of the endogenous polyacid to the endogenous polyamine is 1:0.99-1.

01. Preferably, the reaction in step (1) is carried out under an inert gas atmosphere. Preferably, the reaction temperature in step (1) is 20-30℃. Preferably, the reaction time in step (1) is 30 min-5 h.

7. The production method according to claim 5, wherein In step (2), the mixing comprises: mixing the organic solvent and the inorganic salt in the bifunctional catalyst, then adding the polyamide prepolymer, stirring to dissolve, and then adding the basic compound in the bifunctional catalyst.

8. The production method according to any one of claims 5 to 7, wherein In step (2), the mass ratio of the inorganic salt to the basic compound is 1:0.05-3. Preferably, in step (2), the mass ratio of the inorganic salt to the polyamide prepolymer is 1:2-15.

9. The production method according to claim 5, wherein In step (2), the organic solvent is N,N-dimethylacetamide (DMAc) or N-methyl pyrrolidone (NMP). Preferably, the polymerization temperature in step (2) is 40-160℃. Preferably, the polymerization time in step (2) is 1-24 h. Preferably, the mixing and / or polymerization in step (2) is carried out under an inert gas atmosphere. 10.Use of the biocompatible polyamide of any one of claims 1-4 or prepared by the method of any one of claims 5-9 in the preparation of a drug carrier, a tissue filler or a cosmetic.

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