CN106832303B

CN106832303B - Preparation method of bioabsorbable polyphosphate amino acid copolymer material

Info

Publication number: CN106832303B
Application number: CN201611230767.9A
Authority: CN
Inventors: 王鹏; 刘朋真; 吕国玉; 李鸿; 陈立; 井淋静
Original assignee: Sichuan National Nano Technology Co ltd
Current assignee: Sichuan National Nano Technology Co ltd
Priority date: 2016-12-28
Filing date: 2016-12-28
Publication date: 2020-02-21
Anticipated expiration: 2036-12-28
Also published as: CN106832303A

Abstract

The invention discloses a preparation method of a bioabsorbable polyphosphate amino acid copolymer material, which comprises the following steps of 1) dehydrating α -amino acid and caprolactam under the protection of inert gas at the temperature of 200-.

Description

Preparation method of bioabsorbable polyphosphate amino acid copolymer material

Technical Field

The invention relates to a preparation method of a bioabsorbable polyphosphate amino acid copolymer material, belonging to the field of biomedical degradable materials.

Background

Bioabsorbable materials have been used in medical, environmental, and other fields for a long time. Biodegradable medical materials have been vigorously developed especially in the field of medical and health. General instituteThe absorbable material, i.e. biodegradable material, is a synthetic high molecular organic matter or natural high molecular material, which is hydrolyzed and oxidized in vivo to obtain CO as the final product₂And H₂O, is discharged out of the body through the respiratory system or the urinary system, is not accumulated in the body, has almost no toxic effect, does not need to be taken out again by operation, and has different decomposition and absorption cycles according to different molecular structures and different environmental conditions of the material.

Generally, the most important degradation mechanism of absorbable polymer materials is hydrolysis, but there are distinct degradation rates and degradation periods due to different designs of hydrolysis groups, such as hydrolysis half-lives of 0.1 hour, 4 hours, 3.3 years and 8300 years for decomposition groups of polyanhydrides, acid esters, polyesters and polyamides under nonspecific hydrolysis in the body. Among the factors that influence polymer degradation absorption and strength retention time are mainly the chemical properties of the material, molecular weight distribution, purity, crystallinity, molecular tendency, matrix/reinforcing fiber morphology, porosity, surface properties, size, shape, weight/surface area ratio, local tissue tolerance and clearance, detoxification and storage conditions. Therefore, in clinical application, the degradable polymer material needs to be selected according to different repair cycles of different tissues and organs. Meanwhile, the degradation modes and degradation products of high molecular materials with different chemical compositions are also different, generally, the artificially synthesized high molecular materials are mostly designed into hydrolysable ester bonds, ether bonds, acyl anhydride bonds, amide bonds and the like, the degradation processes are mainly hydrolysis and oxidation reactions, nonspecific enzymes also have certain functions, and finally CO2 and H2O are formed through tricarboxylic acid cycle and are discharged out of a body, such as PGA, PLA and the like, and most of the degradation products are small molecular substances such as carboxylic acids, alcohols and the like which are metabolized by the body and discharged; however, most of the natural polymer absorbable materials applied to the medical field at present have more complex chemical structures, and are hydrolyzed only by the action of enzyme in vivo, and the degradation in vivo is possibly related to the action of other body fluids besides the action of lysozyme and protease. The degradation process in vivo is mainly depolymerization, and most degradation products are neutral polysaccharides and amino acid compounds. From the viewpoint of biosafety, absorbable polymer materials for medical use need to combine not only their degradation rate and degradation mode, but also the safety and efficacy of degradation products.

Nowadays, common absorbable natural polymer materials such as chitosan, chitin fiber, collagen and the like not only show unique non-toxicity, good biocompatibility and good absorbability, but also have excellent biological characteristics such as antibiosis, anti-inflammation, hemostasis and the like, and can promote wound healing, and collagen, chitin and the like have been applied to the fields of surgical sutures, hollow fiber tubes, hemostatic cotton, burn dressings and the like for a long time. However, the application of natural polymer degradable materials in the medical field is greatly limited due to the defects of high material cost, poor processability, immunogenicity, poor mechanical strength, uncontrollable degradation rate and the like.

The artificially synthesized degradable material has the advantages of controllable material source, unlimited quantity and the like, so the clinical application of the material is increasingly increased. Currently, the most widely studied synthetic bioabsorbable polymers have mainly focused on polylactic acid, poly (p-dioxanone), polyglycolic acid, and various combinations of lactide, glycolide copolymers, polytrimethylene carbonate, copolymers of epsilon-caprolactone, and the like. The materials have designability, molecular chain groups can be designed aiming at target products, and the surface performance and the degradation performance of the materials can be correspondingly processed, so that the standardization and the large-scale production are facilitated. Compared with natural high molecular materials, the material has excellent stability and mechanical strength. But also face a number of bottlenecks and problems, such as poor hydrophilicity and low bioactivity; the degradation rate in vivo can not be controlled, the material is degraded, and the material is collapsed, and particularly, the mechanical strength is too fast to be attenuated when the material is applied to bone setting materials; acidic degradation products or materials themselves can stimulate the organism to cause local nonspecific inflammatory reaction and the like.

Nowadays, bioabsorbable polymer materials are more and more paid attention, however, medical technologies are gradually diversified and medical modes of higher quality are pursued, the types and material characteristics of traditional bioabsorbable polymers cannot meet practical requirements, and particularly, the problems of compatibility, acidic degradation products and the like cause the medical application to be limited.

Disclosure of Invention

In view of the above situation, the present invention provides a preparation method of a novel bioabsorbable polyphosphate amino acid copolymer material.

The novel bioabsorbable polyphosphate amino acid copolymer prepared by the method is prepared by polymerizing caprolactam and phosphate and simultaneously introducing α -polybasic amino acid to regulate the biological activity and the degradation performance of the copolymer, wherein caprolactam and α -amino acid are polymerized to form a polybasic amino acid amide structure polymer, and the polybasic amino acid amide structure polymer and the phosphate form the polyphosphate amino acid copolymer.

The method adopts the polymerization of phosphate and caprolactam to modify the polyamide structure, and the whole copolymerization is completed by two steps. On the one hand, the polymerization conditions of caprolactam and phosphate ester monomers are considered, and on the other hand, the conditions of melt polymerization of other amino acids are considered.

The ring-opening polymerization step is basically as follows, firstly caprolactam and other α -amino acid are mixed according to a certain proportion and dissolved in water, the mixture is fully stirred and dehydrated under the conditions of inert gas protection and 150-200 ℃, then the polymerization reaction is carried out under the conditions of 190-260 ℃ to obtain the amide structure high polymer formed by the copolymerization of the polybasic amino acid, the polymerization degree and the molecular weight of the amide structure high polymer material can be increased by increasing the reaction temperature and/or prolonging the reaction time, the degradation rate of the obtained product is correspondingly slowed down, otherwise, the reaction is accelerated, secondly, the phosphate with a certain molar proportion is added after the copolymerization of the polybasic amino acid for a certain time, the synthesis reaction is continued at the temperature of 200-260 ℃, at the moment, the ring opening of the phosphate reacts with the amino group in the amide structure to form a P-N bond, the ring-opening polymerization is finished after 0.5-2 hours, nitrogen is cooled to the room temperature to obtain the polyphosphate amino acid copolymer, simultaneously, the types and the proportion of the other amino acid and the phosphate are adjusted, the copolymer not only can adjust the copolymer water solubility and the degradation period, but also can adjust the degradation environment pH value, and the change of the steps can be 1) the inert gas and the caprolactam react under the conditions of 150-200 ℃ to form the amide structure under the conditions of the inert gas protection, the reaction is finished, the reaction is 1), the reaction is added under the conditions of the inert gas protection of.

The test result shows that the synthesis process of the parent material of the polymer with the multi-amino acid amide structure adopts a segmented mode to obtain more ideal effect, and is beneficial to the adjustment and control of the degradation rate of the parent material. First, after fully stirring and dehydrating under the protection of inert gas, prepolymerization reaction is carried out for 1-3 hours under the conditions of 190-210 ℃, and then the polymerization reaction is completed for 0.5-5 hours under the conditions of 210-260 ℃. The obtained multielement amino acid copolymer parent material has good repeatability and stable process.

Meanwhile, in order to improve the yield of the ring-opening polymerization of phosphate ester, the phosphate ester is pretreated in advance. The pretreatment process mainly carries out purification and water removal. According to different melting points and boiling points of different phosphate ester monomers, distillation purification is carried out, and then anhydrous calcium chloride is adopted for water removal treatment before sample loading.

When the material is prepared by the method, the molar weight of phosphate ester is 0.5-20% of the total molar weight of the raw materials, the molar weight of caprolactam is 40-80% of the total molar weight of the raw materials, the rest components are α -polybasic amino acid, α -polybasic amino acid is formed by copolymerizing epsilon-aminocaproic acid and at least 1 other amino acid, the molar proportion of the epsilon-aminocaproic acid in the total amount of all other amino acids is more than or equal to 50%, and the molar proportion of each amino acid in the rest amino acids in the total amount of all amino acids is controlled to be 0.5-50%.

The copolymer matrix of the invention is mainly the copolymerization of caprolactam and phosphate. The caprolactam and the polyamide high polymer material polymerized by the caprolactam have good mechanical property, barrier property, wear resistance, acid and alkali resistance and good processability. The amido bonds in the molecular chain have larger cohesive force and can form hydrogen bonds, and compared with other polyamide materials, the polyamide material has more alkyl chains (methylene chain segments) in the molecular chain and shows lower melting point and crystallinity. In order to show more flexible degradation performance, a polyester structural unit is introduced into an amide structure to obtain a novel biodegradable material, namely, bioabsorbable polyester amide, wherein the structure simultaneously contains an amide structure and an ester bond, so that the biodegradability is maintained, and the mechanical strength, the flexibility and the like of the biodegradable material are expected to exceed those of aliphatic polyester.

The phosphate polymer is a novel biodegradable medical high polymer material which develops rapidly in recent years, and has good biodegradability and high structural variability. The method can be applied to the medical fields of drug sustained release, tissue engineering, in-vivo development, gene therapy and the like, particularly, the research in drug sustained release materials is very active, and the method has certain advantages in China. The phosphate polyester biodegradable polymer has more advantageous material properties in the biomedical field:

a large amount of phosphate active substances in organisms, and the synthesized phosphate polymer has incomparable good biocompatibility and degradability;

the contents of phosphatase, phosphamidase and tyrosinase in targeted parts (such as focus parts, tumor parts, defect or injury parts and the like) in the body are high, the interaction between cells and materials is strong, and the material function is favorably exerted.

The structure of the phosphate polymer is easy to modify and functionalize, and functional macromolecules can be directly grafted on a polymer side chain or a polymer main chain in a chemical bond mode to endow the polyphosphate matrix with more functions and modifications.

The introduction of the phosphate component greatly improves the reduction of the glass transition temperature of the main chain of the amide structure, improves the hydrophilicity, accelerates the degradation rate, and solves the problems of weak intermolecular force and poor hydrophilicity of the main chain of the amide structure to a certain extent.

Wherein, the phosphate ester is hydrolyzed and copolymerized and dehydrated with caprolactam to form a new P-N bond, and long-range conjugation is not formed, so that a soft P-N skeleton chain can be formed. The P-N skeleton chain has great freedom degree and lower glass transition temperature, and can undergo structural change in a solid state, so that the polymer has the characteristics of good low-temperature elastomer and high plasticity. The cost of material processing is reduced to a certain extent, and the application range of the polyesteramide is widened. On the other hand, the existence of P-O-C group greatly improves the solubility and the processability of the polymer in a common solvent, and particularly has remarkable advantages in slow-release materials.

According to empirical analysis, the selected polymeric phosphate ester compounds are mainly hexabasic phosphate ester and pentabasic phosphate ester. Partial chain transfer reaction exists in the ring-opening polymerization of the hexabasic phosphate, and the obtained product has lower molecular weight but higher polymerization degree; the polymer product of the pentabasic phosphate has higher molecular weight but lower yield, and each has respective advantages, so the phosphate used in the invention is selected from one or more of cyclic phosphate, phenyl dichloro phosphate, methoxy phosphate, ethoxy phosphate, phosphodiester, phosphocyclohexane, phospholane, 2-methyl-phosphocyclohexane, 1, 3-propylene-methyl phosphate, phosphate methoxy acetic acid, isopropyl ethylene phosphate, methyl ethylene phosphate and ethyl ethylene phosphate. The phosphate ester has proved to have good chemical stability and processing property, and the degradation product is nontoxic phosphate ester, alcohol and diol product, and has high biocompatibility. Researches show that the addition of the phosphate can obviously improve the hydrophilicity of aliphatic polyester, polyamide and polycarbonate, accelerate the degradation rate and endow the material with more flexible biodegradation period. On the other hand, phosphate side chains with different functional groups endow the material with more material properties, and the degradability of the polyphosphate amino acid copolymer can be adjusted by adjusting the content of the phosphate.

α -polybasic amino acid is introduced, on one hand, weak alkaline amino acid which is acceptable by human bodies can neutralize acidic degradation products generated in the degradation process of polyphosphate ester, on the other hand, the novel polyester amide copolymer is endowed with better bioactivity and degradability, on the other hand, α -polybasic amino acid in the polyphosphate amino acid copolymer is more ideally copolymerized by epsilon-aminocaproic acid and at least 1 other amino acid, wherein the acidic degradation products comprise one or more of weak alkaline amino acid or neutral amino acid which is acceptable or existing by human bodies, such as gamma-aminobutyric acid, glycine, alanine, phenylalanine, tryptophan, arginine, serine, tyrosine, threonine, leucine, proline, hydroxyproline and lysine.

The novel polyphosphate amino acid copolymer has the advantages that the structure of the polyphosphate is similar to that of a natural phosphorus-containing polymer, the polyphosphate has strong biocompatibility, cell affinity and cell membrane permeability, the structure variability is large, the physical and mechanical properties of materials can be effectively improved, the hydrophilicity and the degradation performance of the polymer are improved, caprolactam can keep the rigidity and the strength of a molecular chain and has the high strength and the flexibility of a common polyamide material, other α -amino acids can adjust the bioactivity and the degradation performance of the copolymer, the three components are organically combined, and the hydrophilicity, the density, the strength, the degradation performance and the forming processing performance of the prepared polyphosphate amino acid copolymer can be adjusted and controlled by adjusting and controlling the components and the content of phosphate, caprolactam and α -amino acid and in-situ polymerization process parameters, so that the polyphosphate amino acid copolymer has very large plasticity and application value.

The polyamide structure is modified by adopting the ring-opening polymerization of phosphate and caprolactam, and the whole ring-opening copolymerization is completed by two steps. On the one hand, the ring-opening conditions of caprolactam and phosphate monomers are considered, and on the other hand, the conditions of melt polymerization of other amino acids are considered.

Firstly, mixing caprolactam and other α -amino acids according to a certain proportion, dissolving in water, fully stirring and dehydrating under the conditions of 150-plus 200 ℃ under the protection of inert gas, carrying out polymerization reaction at the condition of 200-plus 260 ℃ to obtain the amide structure high polymer formed by the copolymerization of the polybasic amino acids, increasing the reaction temperature and/or prolonging the reaction time to increase the polymerization degree and molecular weight of the amide structure high polymer material, correspondingly slowing down the degradation rate of the obtained product, and otherwise, accelerating the reaction, secondly, adding phosphate with a certain molar proportion after the copolymerization of the polybasic amino acids for a certain time, continuing the synthesis reaction at the temperature of 200-plus 260 ℃, wherein the ring opening of the phosphate reacts with amino groups in the amide structure to form P-N bonds, the ring opening polymerization is finished after 0.5-2 hours, cooling nitrogen to room temperature to obtain the polyphosphate amino acid copolymer, and simultaneously adjusting the types and the proportion of the other amino acids, the phosphate and the proportion, not only can adjust the water solubility and the degradation period of the copolymer, but also can adjust the pH value change of the degradation environment.

Through experimental analysis, the more ideal caprolactam and other amino acid types and ratios are as follows: the caprolactam and the epsilon-aminocaproic acid are copolymerized with other two amino acids, wherein the caprolactam accounts for not less than 50 percent of the total molar amount (the total molar amount refers to the total molar amount of the caprolactam, the epsilon-aminocaproic acid and the amino acids) and the epsilon-aminocaproic acid accounts for not less than 25 percent. Meanwhile, the molar ratio of the phosphate ester is controlled to be 2-10% of the total molar amount of all raw materials. The polyphosphate amino acid copolymer prepared under the condition shows more proper hydrophilicity and degradation performance, the hydrophilicity of the copolymer can be controlled between a contact angle of 15-50, and meanwhile, the pH value of a degraded soaking solution is 6.5-7.5, so that the influence on local physiological environment is small, no stimulation reaction is caused, and the polyphosphate amino acid copolymer is most beneficial to cell growth and tissue repair. The simulated body fluid weight loss rate can be controlled within 4-24 weeks, and the degradation period is very wide. Meanwhile, the implant has certain mechanical properties in the early period of implantation, and the compressive strength of the implant can be kept between 45 and 95. On the basis, the degradation performance of the obtained copolymer is regularly changed by further regulating and controlling each process parameter.

Based on the advantages of the bioabsorbable polyphosphate amino acid copolymer, the copolymer can be used as a raw material to prepare a product for repair. The repairing product is a repairing product which is processed by the bioabsorbable polyphosphate amino acid copolymer and is suitable for clinical use. Wherein the repair article is a suture, a tissue fixation device, a tissue and bone screw, a bone plate, a prosthesis, a bone repair filler, a tissue engineering scaffold, a drug delivery device, and a scaffold.

The invention also provides a polymer blend formed by the polyphosphate amino acid copolymer and other materials. The polymer blends of the present invention may contain other conventional components and agents. Other components, additives or agents may be present to provide additional effects to the polymer blends of the present invention, including antimicrobial properties, controlled drug elution, sustained release, and osteointegrative repair factors, among others. The multi-component compounding mode is mainly realized by thermal processing, and can be melt blending in an extruder, including twin-screw blending or single-screw extrusion, co-extrusion, and twin-screw blending with simultaneous degassing screw vacuum devolatilization. Yet other possible thermal processing methods may include methods selected from the group consisting of: injection molding, compression molding, blow molding, blown film, thermoforming, film extrusion, fiber extrusion, sheet extrusion, profile extrusion, coextrusion, foam injection molding. The resulting blend at a later stage can be sized by conventional means such as granulation, pelletization and grinding.

For example, the polyphosphate amino acid copolymer composite material for bone defect repair can be extruded using screw extrusion equipment in the conventional form of single/twin screw extruders presently reported and/or used to form a controllably degradable polyphosphate amino acid copolymer composite bone implant material, wherein the bone-binding agent or filler is primarily a suitable bioglass or ceramic component, but is not limited to silicates and calcium phosphates, such as tricalcium silicate, dicalcium silicate, magnesium silicate, modified magnesium silicate, hydroxyapatite, substituted apatite, α and β tricalcium phosphate, octacalcium phosphate, calcium hydrogen phosphate, dicalcium phosphate, metaphosphate, pyrophosphate, phosphate glass, carbonates, sulfates, oxides, and chlorides of calcium and magnesium, and combinations thereof, and specifically, can be a blend of a bioabsorbable polyphosphate amino acid copolymer with calcium sulfate, calcium hydrogen phosphate, wherein the weight ratio of the polyphosphate amino acid copolymer, calcium sulfate, and calcium hydrogen phosphate is 100: 68.75 g: 81.25, or a blend of a bioabsorbable polyphosphate amino acid copolymer with hydroxyapatite, wherein the weight ratio of the polyphosphate amino acid copolymer to hydroxyapatite is 150% by weight, and the total phosphate is preferably about 150% by weight ratio of the polyphosphate amino acid copolymer, and the hydroxyapatite is crushed at a later stage of the porous calcium phosphate is preferably about 150% by weight of the stage of the porous calcium phosphate.

The porous scaffolds are not limited to use in bone repair, and are compounded with multiple biological agents to form prosthetic implant materials with different biological activities, such as the addition of antimicrobial agents, including polychlorophenoxyphenol, triclosan, diphenylmethane derivatives.

Although not preferred, the medical devices of the present invention may comprise non-absorbable polymers in addition to the absorbable polymer blends of the present invention. Examples of such devices include bone screws, bone plates, prostheses. Suitable nonabsorbable polymers include, but are not limited to: an acrylic resin; polyamide-imide (PAI); imide (PEEK); a polycarbonate; thermoplastic polyolefins, such as Polyethylene (PE), polypropylene (PP); polyamides (PA), such as nylon 6 and nylon 66; polymethylmethacrylate (PMMA) and combinations and equivalents thereof.

Bioabsorbable medical devices of the present invention thus made from the polymer blends of the present invention include, but are not limited to, conventional medical devices, particularly implantable medical devices, including sutures, tissue fixation devices, tissue and bone screws, bone plates, prostheses, bone repair fillers, tissue engineering scaffolds, drug delivery devices, and stents.

Aiming at the defects of the traditional artificial material which can be absorbed biologically, the invention adopts the ring-opening polymerization of caprolactam and phosphate ester, and simultaneously adds natural amino acid which can be absorbed by human body to regulate the novel filling type degradation performance of polyphosphate amino acid copolymer. Compared with the traditional degradable high polymer, the novel polyphosphate amino acid copolymer has the following advantages: 1, the copolymerization of phosphate and caprolactam can obviously improve the hydrophilicity, low crystallinity, low relative molecular mass, high molecular chain linearization degree, larger specific surface area and the like of a polyamino acid matrix, and the polyamino acid matrix can be more easily absorbed by tissues and has higher bioactivity; the caprolactam and the phosphate ester are subjected to ring-opening polymerization to form a P-N bond, so that the polymer bond has high degree of freedom and lower glass transition temperature, and can undergo structural change when being solidified, so that the low-temperature elastomer has good low-temperature elasticity and higher processing performance, can be plastically formed into different shapes such as granules, rods, blocks and the like, and has various clinical indications; 3, the novel polyphosphate amino acid copolymer can control the degradation speed through the types and the molecular weight of amino acid and the content of phosphate ester, the degradation period is controllable, and the medical application of the polyphosphate material is expanded; 4, in the whole degradation and absorption process, the pH value is kept between 6.0 and 7.5, the neutral environment is realized, the cell growth is facilitated, the side effects such as inflammation, toxicity and allergy are not generated, meanwhile, the degradation products mainly comprise phosphate and amino acid monomers, most of the degradation products are nutrient substances of cells, the degradation products can provide nutrition for tissues in the absorption process, and the tissue degradation and absorption process is not only beneficial to the formation of new tissues and rapid growth and healing; 5. good mechanical property.

In conclusion, the polyphosphate amino acid copolymer prepared by the method has good hydrophilicity and degradation performance and excellent mechanical property, the pH value of a degradation product is 6.5-7.5, no stimulation reaction is caused, the effect of in vivo repair is excellent, and the clinical application prospect is good.

Obviously, many modifications, substitutions, and variations are possible in light of the above teachings of the invention, without departing from the basic technical spirit of the invention, as defined by the following claims.

The present invention will be described in further detail with reference to the following examples. This should not be understood as limiting the scope of the above-described subject matter of the present invention to the following examples. All the technologies realized based on the above contents of the present invention belong to the scope of the present invention.

Drawings

FIG. 1 is a schematic view of a vertebral body support

FIG. 2 a schematic view of a cervical fusion cage

Detailed Description

The raw materials used in this example were purchased from Shanghai Xusen non-halogen Smoke prevention flame retardant, Inc.

Example 1

Respectively taking and adding caprolactam, 6-aminocaproic acid and gamma-aminobutyric acid into a 250ml three-necked bottle, wherein 55.17g (0.4875mol), 31.94g (0.2438mol) and 25.14g (0.2437mol) are respectively added, adding 70ml of distilled water, introducing nitrogen for protection, stirring and gradually heating to 150-200 ℃ for slow dehydration, carrying out prepolymerization reaction for 0.5 hour after dehydration is completed, heating to 210 ℃ for polymerization for 1.5 hour, adding 7.15g (0.025mol) of cyclic phosphate obtained after calcium chloride is dehydrated, heating to 220 ℃ for ring opening reaction for 1 hour, and cooling to room temperature under the protection of nitrogen to obtain 101.4g of light yellow solid. The obtained polyphosphate amino acid copolymer is crushed into particles of 1-3 mm. The content of polyphosphate in the copolymer was 2.5%.

The polyphosphate amino acid copolymer is subjected to in-vitro simulated body fluid soaking experiment, clear water character test and L929 fibroblast culture experiment by using an extracting solution thereof. The weight loss of the simulated body fluid is 58 percent after the simulated body fluid is soaked for 12 weeks, and the pH value is kept between 6.7 and 7.3 in the degradation process. The result of the hydrophilicity test shows that the contact angle is 43, and after L929 fibroblasts are cultured by the test sample extracting solution for 72 hours, the cell proliferation rate is 120 percent and the toxicity is 0 grade by the MTT method.

Examples 2 to 4

Respectively taking 56.01g,53.75g,50.92g, 32.42g,31.11g,29.48g, 25.52g,24.49g and 23.20g of caprolactam, 6-aminocaproic acid and gamma-aminobutyric acid, respectively, adding into a 250ml three-necked bottle, adding 70ml of distilled water, introducing nitrogen for protection, stirring, gradually heating to 150-200 ℃ for slow dehydration, carrying out prepolymerization for 0.5 hour after the dehydration is finished, heating to 210 ℃ for polymerization for 1.5 hours, respectively adding 2.86g, 14.3g and 28.6g of calcium chloride dehydrated cyclic phosphate, heating to 220 ℃ for ring opening reaction for 1 hour, and cooling to room temperature under the protection of nitrogen to obtain the copolymer of polyphosphate with different contents, wherein the contents are respectively 1%, 5% and 10%. The obtained polyphosphate amino acid copolymer is crushed into particles of 1-3 mm.

The polyphosphate amino acid copolymer is subjected to in-vitro simulated body fluid soaking experiment, clear water character test and L929 fibroblast culture experiment by using an extracting solution thereof. The weight loss of 1%, 5% and 10% polyphosphate amino acid copolymer after soaking in simulated body fluid for 12 weeks is 41%, 68% and 89%, respectively, and the pH value is kept at 6.2-7.4 in the degradation process. The results of the hydrophilicity test showed contact angles of 57, 35 and 27, respectively, and the cell proliferation rates of 120%, 115% and 106% and the toxicity of 0 grade were calculated by the MTT method after L929 fibroblasts were cultured with the extract of the test sample for 72 hours. It is shown that the higher the hydrophilicity of the polyamide copolymer is, the faster the degradation rate is, the more the cyclic phosphate content is increased.

Example 5

Respectively taking 55.17g, 30.04g, 23.11g, 3g and 5g of caprolactam, 6-aminocaproic acid, gamma-aminobutyric acid, lysine and proline, respectively, adding into a 250ml three-necked bottle, adding 70ml of distilled water, introducing nitrogen for protection, stirring, gradually heating to 150-200 ℃ for slow dehydration, performing prepolymerization reaction for 0.5 hour after dehydration, heating to 210 ℃ for polymerization for 1.5 hours, adding 7.15g of calcium chloride dehydrated cyclic phosphate, heating to 220 ℃ for ring-opening reaction for 1 hour, and cooling to room temperature under the protection of nitrogen to obtain 103.17g of light yellow solid. The obtained polyphosphate amino acid copolymer is crushed into particles of 1-3 mm. The content of polyphosphate in the copolymer was 2.5%.

The polyphosphate amino acid copolymer is subjected to in-vitro simulated body fluid soaking experiment, clear water character test and L929 fibroblast culture experiment by using an extracting solution thereof. The weight loss of the simulated body fluid after being soaked for 12 weeks is 67 percent, and the pH value is kept between 6.6 and 7.4 in the degradation process. The result of the hydrophilicity test shows that the contact angle is 40, and after L929 fibroblasts are cultured by the test sample extracting solution for 72 hours, the cell proliferation rate is 118 percent and the toxicity is 0 grade calculated by an MTT method.

Example 6

Respectively taking and adding 55.17g, 44.68g, 2.4g, 5.9g, 2g and 4.6g of caprolactam, 6-aminocaproic acid, alanine, phenylalanine, lysine and proline into a 250ml three-necked bottle, adding 70ml of distilled water, introducing nitrogen for protection, stirring and gradually heating to 150-200 ℃ for slow dehydration, carrying out prepolymerization for 0.5 hour after dehydration is finished, heating to 210 ℃ for polymerization for 1.5 hours, adding 7.15g of cyclic phosphate after calcium chloride is dehydrated, heating to 220 ℃ for ring opening reaction for 1 hour, and cooling to room temperature under the protection of nitrogen to obtain 97.1g of light yellow solid. The obtained polyphosphate amino acid copolymer is crushed into particles of 1-3 mm. The content of polyphosphate in the copolymer was 2.5%.

The polyphosphate amino acid copolymer is subjected to in-vitro simulated body fluid soaking experiment, clear water character test and L929 fibroblast culture experiment by using an extracting solution thereof. The weight loss of the simulated body fluid is 47 percent after the simulated body fluid is soaked for 12 weeks, and the pH value is kept between 6.6 and 7.2 in the degradation process. The result of the hydrophilicity test showed that the contact angle was 51, and the cell proliferation rate was 123% and the toxicity was 0 grade, as calculated by the MTT method, after L929 fibroblasts were cultured with the test sample extract for 72 hours.

Examples 7 to 10

Respectively taking 55.17g, 31.94g and 25.14g of caprolactam, 6-aminocaproic acid and gamma-aminobutyric acid, respectively, adding into a 250ml three-necked bottle, adding 70ml of distilled water, introducing nitrogen for protection, stirring, gradually heating to 150-200 ℃ for slow dehydration, carrying out prepolymerization reaction for 0.5 hour after the dehydration is finished, heating to 210 ℃ for polymerization reaction for 1.5 hours, respectively adding 5.4g of calcium chloride dehydrated phenyl dichlorophosphate, 7.93g of methoxy cyclic phosphate, 3.46g of dioxaphosphorinane and 8.23g of methyl vinyl phosphate, heating to 220 ℃ for ring opening reaction for 1 hour, and cooling to room temperature under the protection of nitrogen to obtain the copolymer containing the corresponding polyphosphate. The content of polyphosphate in the copolymer is 2.5 percent.

The polyphosphate amino acid copolymer is subjected to in-vitro simulated body fluid soaking experiment, clear water character test and L929 fibroblast culture experiment by using an extracting solution thereof. Weight loss after soaking four polyphosphate amino acid copolymers in simulated body fluid for 12 weeks is 65%, 51%, 74% and 63%, and pH is kept at 6.0-7.4 in the degradation process. The results of the hydrophilicity test showed contact angles of 49, 46, 57 and 61, and the cell proliferation rates of 98%, 104%, 113% and 106% and the toxicity of 0 grade were calculated by the MTT method after L929 fibroblasts were cultured for 72 hours using the extract of the test sample. The result shows that different cyclic phosphate functionalities under the same synthesis conditions have significant influence on the polyamide structure, and cyclic phosphates with different functional groups can be selected for ring-opening copolymerization according to the later-stage material application.

Examples 11 to 12

Respectively taking 55.17g, 31.94g and 25.14g of caprolactam, 6-aminocaproic acid and gamma-aminobutyric acid, respectively, adding into a 250ml three-necked bottle, adding 70ml of distilled water, introducing nitrogen for protection, stirring, gradually heating to 150-200 ℃ for slow dehydration, respectively performing prepolymerization for 0.5 and 1 hour after dehydration, respectively heating to 210 ℃ and 220 ℃ for polymerization for 0.5 and 3 hours, adding 7.15g of cyclic phosphate after calcium chloride is dehydrated, respectively performing ring opening reaction for 1 hour at 220 ℃ and ring opening reaction for 1 hour at 230 ℃, and then cooling to room temperature under nitrogen protection to respectively obtain polyphosphate amino acid copolymers with different reaction temperatures and times. The obtained polyphosphate amino acid copolymer is crushed into particles of 1-3 mm. The content of polyphosphate in the copolymer was 2.5%.

The polyphosphate amino acid copolymer is subjected to in-vitro simulated body fluid soaking experiment, clear water character test and L929 fibroblast culture experiment by using an extracting solution thereof. The weight loss of the two simulated body fluids after being soaked for 12 weeks is respectively 100 percent (complete degradation in 10 th week) and 36 percent, and the pH value is kept between 6.5 and 7.3 in the degradation process. The results of the hydrophilicity test showed contact angles of 36 and 58, and the cell proliferation rates of 110% and 116% and the toxicity of 0 grade were calculated by the MTT method after L929 fibroblasts were cultured for 72 hours using the extract of the test sample. Comparative experiments show that the polymerization conditions have a significant influence on the degradation properties of the copolymers.

Example 13

Respectively taking 55.17g, 31.94g and 25.14g of caprolactam, 6-aminocaproic acid and gamma-aminobutyric acid, respectively, adding into a 250ml three-necked bottle, adding 70ml of distilled water, introducing nitrogen for protection, stirring, gradually heating to 150-200 ℃ for slow dehydration, performing prepolymerization reaction for 0.5 hour after dehydration, heating to 210 ℃ for polymerization reaction for 1.5 hours, adding 7.15g of cyclic phosphate after calcium chloride is dehydrated, heating to 220 ℃ for ring opening reaction for 1 hour, and cooling to room temperature under the protection of nitrogen to obtain 102.6g of light yellow solid. The obtained polyphosphate amino acid copolymer is crushed into particles of 1-3 mm. The content of polyphosphate in the copolymer was 2.5%.

100g of polyphosphate amino acid copolymer, 68.75g of calcium sulfate and 81.25g of calcium hydrophosphate are fully mixed and extruded. The temperature of each section of the material cylinder during extrusion molding is 145 ℃ (head), 140 ℃, 135 ℃, 130 ℃, 125 ℃, 100 ℃ and the feeding frequency is 30 Hz. After extrusion molding, the polyphosphate amino acid copolymer-calcium phosphate composite material is obtained, and the composite material with the diameter of 2-5mm is obtained by crushing. The content of calcium and phosphorus salt in the compound is 60%, and the Ca/P ratio is 1.67 by analysis. The copolymer compound is soaked in simulated body fluid for 24 weeks, the weight loss is 48% in the first 4 weeks and 65% in the first 12 weeks, and the pH value is kept between 6.7 and 7.3 in the degradation process.

After L929 fibroblasts are cultured for 72 hours by using the extract of the compound, the cell proliferation rate is 131 percent and the toxicity is 0 grade by using an MTT method.

Example 14

100g of polyphosphate amino acid copolymer and 150g of hydroxyapatite are fully mixed and extruded. The temperature of each section of the material cylinder during extrusion molding is 145 ℃ (head), 140 ℃, 135 ℃, 130 ℃, 125 ℃, 100 ℃ and the feeding frequency is 30 Hz. After extrusion, the mixture is foamed (the foaming agent is azodicarbonamide) and injection-molded into a porous composite material, and the porous composite material is processed into a porous block material with the diameter of 5 multiplied by 5 mm. The content of calcium and phosphorus salt in the compound is 60%, and the Ca/P ratio is 1.67 by analysis. The copolymer compound is soaked in simulated body fluid for 24 weeks, the weight loss in the first 4 weeks is 18%, the weight loss in the first 12 weeks is 26%, the weight loss in the first 24 weeks is 31%, and the pH value is kept between 6.7 and 7.3 in the degradation process.

After L929 fibroblasts are cultured for 72 hours by using the extract of the compound, the cell proliferation rate is 121 percent and the toxicity is 0 grade by using an MTT method. Meanwhile, 0.5mL of bovine serum albumin solution of 1mg/mL is added into the porous material, and the release condition of the serum protein is observed, so that the bovine serum albumin can be continuously released after being soaked in the deionized water, and the release amount of the serum protein of 40ng still exists after 4 weeks.

Examples 15 to 16

Taking the extruded composite material of example 14, various products required by clinic are prepared by adopting the conventional injection molding, hot pressing and the like. Taking the preparation of the vertebral body support shown in FIG. 1 as an example, a cervical vertebra fusion device mold is adopted to perform injection molding under the injection molding temperature range of 150-; taking the preparation of the cervical vertebra fusion cage shown in fig. 2 as an example, plasticizing for 5-10 minutes at 170 +/-10 ℃ by adopting a hot pressing mode and a corresponding mold, and cooling to obtain a corresponding product.

Comparative example 1

Respectively taking 56.58g, 32.79g and 25.78g of caprolactam, 6-aminocaproic acid and gamma-aminobutyric acid, respectively, adding the caprolactam, the 6-aminocaproic acid and the gamma-aminobutyric acid into a 250ml three-necked bottle, adding 70ml of distilled water, introducing nitrogen for protection, stirring, gradually heating to 150-200 ℃ for slow dehydration, performing prepolymerization reaction for 0.5 hour after the dehydration is completed, heating to 210 ℃ for polymerization for 1.5 hours, cooling to room temperature to obtain a poly-amino acid material, and crushing into particles with the particle size of 1-3 mm.

The weight loss of the simulated body fluid is 42 percent after the simulated body fluid is soaked for 12 weeks, and the pH value is kept between 6.6 and 7.2 in the degradation process. The result of the hydrophilicity test showed that the contact angle was 71, and the cell proliferation rate was 93% and the toxicity was 0 grade, as calculated by the MTT method, after L929 fibroblasts were cultured with the test sample extract for 72 hours. It can be seen that the addition of the cyclic phosphate can obviously improve the hydrophilicity of the polyamide material, improve the activity on cells and simultaneously improve the degradation rate of the material.

Comparative example 2

Adding 133.16g of caprolactam into a three-necked bottle, adding 70ml of distilled water, introducing nitrogen for protection, stirring, gradually heating to 150-200 ℃ for slow dehydration, performing prepolymerization for 1 hour after dehydration, heating to 230 ℃ for polymerization for 1.5 hours, cooling to room temperature to obtain a polyamide material, and crushing into particles with the particle size of 1-3 mm. The weight loss is only 5% after soaking in simulated body fluid for 12 weeks, and the pH value is kept between 6.9 and 7.3 in the degradation process. It can be seen that the addition of other amino acids increases the degradation rate of the material.

The polyphosphate ester polymer obtained by adopting the steps of ring-opening polymerization, chlorination, substitution and the like of dioxaphosphorinane is completely degraded after being soaked in simulated body fluid for 2 days, and has the advantages of rubber-like property at normal temperature and 13MPa compressive strength due to lower crystallization temperature, so that the mechanical strength of the polyphosphate ester copolymer can be greatly improved by adding amide structures such as caprolactam and the like, and the degradation period of the polyphosphate ester copolymer can be prolonged.

Claims

1. A method for preparing polyphosphate amino acid copolymer, which is characterized by comprising the following steps: the method comprises the following steps:

1) dehydrating α -amino acid and caprolactam under the protection of inert gas and the conditions of 150 ℃ and 200 ℃;

2) firstly, carrying out prepolymerization reaction for 1-3 hours at the temperature of 190-;

3) adding phosphate, reacting at 200-260 ℃ for 0.5-2h to complete ring-opening copolymerization, and cooling to room temperature under the protection of inert gas;

the polyphosphate amino acid copolymer is prepared from caprolactam, α -amino acid and phosphate, wherein caprolactam and α -amino acid are polymerized to form a multi-amino acid amide structure polymer, the multi-amino acid amide structure polymer and phosphate form a polyphosphate amino acid copolymer, α -amino acid in the polyphosphate amino acid copolymer is a mixture of epsilon-aminocaproic acid and weakly alkaline or neutral amino acid, wherein the weakly alkaline or neutral amino acid is one or more of gamma-aminobutyric acid, glycine, alanine, phenylalanine, tryptophan, arginine, serine, tyrosine, threonine, leucine, proline, hydroxyproline and lysine, the mole percentages of the caprolactam, the α -amino acid and the phosphate in the polyphosphate amino acid copolymer are that the mole ratio of the phosphate is 0.5-20% of the total mole amount, the mole amount of the caprolactam is 40-80% of the total mole amount, and the balance is α -amino acid, and the mole ratio of the epsilon-aminocaproic acid in the α -amino acid is not less than 50%, and the mole ratio of the balance amino acid is 0.5-50%.

2. The method of claim 1, wherein: the molar weight of the phosphate ester is 2-10% of the total molar weight of the raw materials.

3. The method according to any one of claims 1 to 2, wherein: in the polymer with the polybasic amino acid amide structure, the molar ratio of the caprolactam consumption is not less than 50%.

4. The method of claim 1, wherein: in the polyphosphate amino acid copolymer, the phosphate is one or the combination of more than two of cyclic phosphate, phenyl dichloro phosphate, dioxaphosphorinane lactam phosphate, isopropyl ethylene phosphate, methyl ethylene phosphate and ethyl ethylene phosphate.

5. The method of claim 1, wherein: in the step 3), phosphate is pretreated according to the following method: anhydrous calcium chloride was added to the phosphate to conduct dehydration treatment.