CN114479037B

CN114479037B - Biodegradable polyester elastomer material and preparation method thereof

Info

Publication number: CN114479037B
Application number: CN202111589684.XA
Authority: CN
Inventors: 贾亚听; 何创龙; 隋晓锋
Original assignee: Donghua University
Current assignee: Donghua University
Priority date: 2021-12-23
Filing date: 2021-12-23
Publication date: 2022-11-25
Anticipated expiration: 2041-12-23
Also published as: CN114479037A

Abstract

The invention relates to a biodegradable polyester elastomer material and a preparation method thereof, which is obtained by carrying out melt condensation polymerization on monomers containing sebacic acid, glycerol, citric acid and L-cysteine. The polyester elastic material provided by the invention has good elasticity, biocompatibility and biodegradability, and molecular chains of the polyester elastic material are rich in active reactive functional groups of carboxyl and sulfydryl simultaneously, so that the polyester elastic material is convenient for functional modification, and has application prospects in different biomedical application fields.

Description

Biodegradable polyester elastomer material and preparation method thereof

Technical Field

The invention belongs to the technical field of polyester materials, and particularly relates to a biodegradable polyester elastomer material and a preparation method thereof.

Background

Biodegradable polyester materials are the most important class of materials in biodegradable synthetic polymer materials, and due to good biodegradability, the biodegradable polyester materials are receiving more and more attention and are widely used in various biomedical applications. Existing biodegradable polyester materials mainly include two broad classes, thermoplastic and thermosetting. Generally, thermoplastic polyesters have better mechanical strength, but have poor elasticity and slow degradation, such as polylactic acid (PLA), polycaprolactone (PCL), and copolymers thereof, while thermosetting polyesters have better elasticity and degradability, such as polytrimethylene sebacate (PGS). Most of human tissues are soft tissues and are in certain dynamic environments, such as cardiac muscle, blood vessels, skin, organs and the like, and when the implant is used in the parts, the implant is constructed by selecting a material with better elasticity, so that the implant is more favorable for being matched with the human tissues. In addition, if the implant has a certain bioactivity, it will be more beneficial to have a beneficial interaction with the microenvironment in the body, to have a better functioning or to promote tissue repair. However, the existing biodegradable polyester elastic materials are mainly used as structural materials to provide mechanical support for various tissue engineering scaffolds or medical application devices, and maintain the structural integrity or mechanical matching requirements of the materials, and the materials are mostly chemically inert, and the molecular chains of the materials lack reactive functional groups. For example, molecular chains of PLA, PGA, and PCL are composed of ester bonds and fatty chains, and have no additional functional groups, while molecular chains of PGS have many-OH groups attached thereto, but have low-OH activity and are difficult to further react at room temperature. In short, the existing biodegradable polyester materials are difficult to directly modify the bioactivity because of lack of reactive functional groups on molecular chains. For functional modification of these materials, stents or devices, surface modification or blending modification of the materials is required, such as plasma or chemical agent treatment to generate some reactive functional groups on the surface of the materials, or blending with biological macromolecules with biological activity. This undoubtedly increases the complexity of the application, and in most cases these methods have some limitations, which cannot be flexibly adopted, and thus, it increases the difficulty for the practical application. Therefore, the development of biodegradable polyester elastic materials having reactive functional groups contributes to the flexible functionalization of tissue engineering scaffolds or medical devices, and is of great significance in promoting various developments and advances in the biomedical field.

Disclosure of Invention

The invention aims to solve the technical problem of providing a biodegradable polyester elastomer material and a preparation method thereof.

The invention relates to a polyester elastomer material shown in the following structure,

wherein n is more than or equal to 1,R = H or-COCH ₂ -or-CH ₂ -。

The polyester elastomer is obtained by carrying out melt condensation reaction on raw materials containing sebacic acid, glycerol, citric acid and L-cysteine.

The invention provides a preparation method of a polyester elastomer material, which comprises the following steps:

melting monomers: mixing sebacic acid, glycerol, citric acid and L-cysteine, stirring under protective gas until the monomers are molten, and making a reaction system into a clear and transparent liquid;

esterification reaction: stirring the reaction system under normal pressure to carry out esterification reaction;

prepolymerization: reducing the reaction pressure, keeping a certain vacuum degree, continuously stirring the reaction system to react for a certain time for condensation polymerization to obtain a branched prepolymer with a certain molecular weight;

curing of the prepolymer: and (3) continuously reacting the purified or unpurified prepolymer at a certain temperature and under a certain pressure for a certain time to obtain the polyester elastomer material with certain elasticity.

The preferred mode of the above preparation method is as follows:

the molar ratio of the sebacic acid to the glycerol is 1; the molar ratio of sebacic acid to citric acid is 1:0.001-0.6; the molar ratio of sebacic acid to L-cysteine is 1.

The melting temperature under the protective gas is 120-200 ℃; the protective gas is nitrogen, argon, helium and the like.

Further preferably, the melting temperature is 130 to 180 ℃.

Adding or not adding a catalyst after the melting; the catalyst is one of stannous octoate, stannous chloride, stannous octoate/p-toluenesulfonic acid and stannous chloride/p-toluenesulfonic acid.

The temperature of the esterification reaction is 120-200 ℃, and the time is 0.01-20h.

Further preferably, the temperature of the esterification reaction is 120-160 ℃ and the reaction time is 0.01-20 hours.

The reaction under vacuum condition is as follows: the reaction temperature is 100-220 ℃, the vacuum degree of the reaction system is 0.1-6000Pa, and the reaction time is 0.5-50h; the prepolymer is purified.

Further preferably, the reaction temperature under the vacuum condition is 100-180 ℃, the vacuum degree of the reaction system is 0.1-6000Pa, and the reaction time is 0.5-50 hours.

The prepolymer purification steps are as follows: dissolving the prepolymer in a certain solvent, then dripping the polymer solution into deionized water for precipitation, and collecting the precipitate to obtain the purified prepolymer; the solvent in which the prepolymer is dissolved includes one or more of methanol, ethanol, acetone, tetrahydrofuran, N-dimethylformamide, dimethyl sulfoxide, dichloromethane, acetonitrile, and the like.

Preferably, the prepolymer is purified from 0 to 5 times.

The curing is as follows: the temperature is 50-180 ℃, the vacuum degree in the curing process is 0.1-6000Pa, and the curing time is 4-200h.

The polyester elastomer material disclosed by the invention is applied to compounding PGSCC with other natural or artificial synthetic materials, so that the obtained compound has reactive functional groups of carboxyl and sulfydryl, and is convenient for functional modification. More specifically, for example, PGSCC and PLLA are used in a composite manner, a composite nanofiber membrane with carboxyl and sulfhydryl groups attached to the fiber surface is obtained through an electrospinning technology, some bioactive molecules such as cytokines, drugs and the like are grafted on the fiber surface by utilizing the reactivity of the carboxyl and the sulfhydryl groups, and the mechanical properties such as elasticity, modulus and the like of the composite fiber membrane are improved due to the introduction of the PGSCC, so that the obtained composite nanofiber membrane is more suitable for dura mater repair, wound healing, tissue regeneration and the like.

The invention specifically relates to a method for preparing a crosslinked polyester elastomer, which is characterized in that four monomers of sebacic acid, glycerol, citric acid and L-cysteine are melted, esterified under the action of a catalyst or no catalyst, then melted and condensed to form a branched high-molecular prepolymer, and the prepolymer is continuously solidified to form a crosslinked polyester elastomer with certain elasticity, namely poly (sebacic acid-citric acid-L-cysteine-glycerol) ester (abbreviated as PGSCC). The polyester elastic material has good biocompatibility, biodegradability and mechanical elasticity, and the molecular chain of the polyester elastic material is simultaneously rich in reactive functional groups of carboxyl and sulfydryl, so that functional modification is facilitated, and the polyester elastic material is a biodegradable polyester elastic material with both structural and functional properties.

Advantageous effects

(1) The reaction monomers adopted by the invention are metabolites or metabolic intermediates in vivo, and the biological safety is good.

(2) The obtained polyester elastic material has good elasticity, biocompatibility and biodegradability.

(3) The molecular chain of the obtained polyester elastic material is rich in reactive carboxyl and sulfydryl, namely, the polyester elastic material has two active functional groups at the same time, so that the polyester elastic material is convenient for functional modification and can be used as a functional elastic material.

Drawings

FIG. 1 is an infrared spectrum (FTIR) of the material obtained in example 1; 1732cm ^-1 Is the absorption peak of ester C = O, 1716cm ^-1 The peak is the absorption peak of carboxyl C = O, and the PGSCC spectrum shows more absorption peaks of carboxyl C = O than PGS, indicating that PGSCC is rich in carboxyl groups (-COOH) in the molecular chain.

FIG. 2 shows the NMR spectrum of the material obtained in example 1 ( ¹ H-NMR); the peak at delta 1.06ppm on the PGSCC spectrum is assigned to the sulfhydryl hydrogen (-CH) ₂ -SH) This indicates that molecular chains of PGSCC are rich in mercapto groups (-SH).

FIG. 3 is a graph of uniaxial tensile stress-strain for the material obtained in example 2; the test temperature was room temperature and the stretching rate was 20mm/min.

FIG. 4 is a graph of cyclic tensile stress-strain for the material obtained in example 2; the test temperature is room temperature, the stretching rate is 10mm/min, the strain range is 5-50%, the cycle times are 10 times, and the residence time between cycles is 0s.

FIG. 5 is a fluorescence micrograph of two nanofibers obtained from example 3.

FIG. 6 shows the results of experiments in which PGSCC obtained in example 2 supported cell proliferation. In particular to an experimental result of the gradual proliferation of mouse fibroblast (NIH 3T 3) on the surface of the material along with the increase of time, and the test method is a CCK-8 method.

FIG. 7 shows the results of in vitro degradation experiments of PGSCC obtained in example 2; wherein (a) is the result of mass loss of the sample with increasing incubation time; b is the result of the change of the pH of the sample soaking solution along with the increase of the incubation time.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Example 1

(1) Adding 0.12mol of sebacic acid (national drug, AR), 0.08mol of glycerol (national drug, AR), 0.006mol of citric acid (national drug, AR) and 0.012mol of L-cysteine (national drug, AR) into a 250ml two-neck flask, stirring for 0.5h at 160 ℃ under the protection of nitrogen, completely melting the monomers, and forming a clear and transparent liquid by the system;

cooling to 140 ℃, and stirring for reaction for 4 hours;

(3) Reducing the pressure to 3325Pa at 140 ℃, and stirring for reaction for 12h to obtain a prepolymer; (4) The prepolymer was dissolved by adding 100ml of ethanol, and then added dropwise to 400ml of deionized water, and the precipitate was collected and dried to obtain a purified prepolymer. (5) The prepolymer was cured at 100Pa at 80 ℃ for 60 hours to give a cured polyester elastomer (PGSCC).

Example 2

(1) Adding 0.12mol of sebacic acid (national drug, AR), 0.08mol of glycerol (national drug, AR), 0.03mol of citric acid (national drug, AR) and 0.015mol of L-cysteine (national drug, AR) into a 250ml two-neck flask, stirring for 0.5h at 160 ℃ under the protection of nitrogen, completely melting the monomers, and forming a clear and transparent liquid by the system;

(2) The temperature is reduced to 140 ℃, and the stirring reaction is carried out for 2 hours;

(3) Reducing the pressure to 3325Pa at 140 ℃, and stirring for reaction for 8h to obtain a prepolymer;

(4) Adding 100ml ethanol to dissolve the prepolymer, adding dropwise 400ml deionized water, collecting precipitate, drying to obtain purified prepolymer, and measuring its molecular weight by GPC as M _n ＝3467(PDI＝16.58)；

(5) The prepolymer was cured at 100Pa, 80 ℃ for 24h to give a cured polyester elastomer (PGSCC).

The resulting material PGSCC was subjected to uniaxial tensile testing with the comparative material PGS. The samples were rectangular bars 20mm long/5 mm wide/1 mm thick, the test temperature was room temperature, the tensile rate was 20mm/min, and the clamp spacing was 10mm, as shown in fig. 3, and the results showed that the stress-strain curve of PGSCC was similar to that of typical vulcanized rubber, indicating that it was in a high elastic state at room temperature and had better elasticity, as shown by the tensile strength of PGSCC of 0.3-0.5MPa, modulus of elasticity <0.5MPa, and elongation at break >180%.

The resulting material PGSCC was subjected to a cyclic tensile test with the comparative material PGS. The sample is a rectangular strip with the length of 20 mm/width of 5 mm/thickness of 1mm, the test temperature is room temperature, the stretching rate is 10mm/min, the strain range is 5-50%, the cycle time is 10 times, the residence time between cycles is 0s, and the distance between clamps is 10mm. As shown in FIG. 4, the results indicate that PGSCC has good elasticity in the 5-50% strain range, and can be cyclically stretched without hysteresis loop on the cyclic stretching curve, and the stretching curve after 10 cycles of stretching almost completely coincides with the initial curve.

And (3) evaluating the cell compatibility of the obtained PGSCC material, wherein the test method is a CCK-8 method. Taking mouse fibroblast (NIH 3T 3), and adding 1.0 × 10 ⁴ /cm ² The number of the cells is planted on the surface of the material, the cells are incubated in a 37 ℃ cell incubator, the culture solution is discarded on

days

1, 3 and 5 after the cells are inoculated, PBS is washed for 2 times, CCK-8 test solution is added, incubation is carried out for 2h at 37 ℃, 100 mul of test solution is taken to measure the absorbance of the cells at 450nm, the larger the absorbance is, the larger the number of the cells is, and as shown in figure 6, the result shows that PGSCC can support the growth of the cells and has good cell compatibility.

And (3) evaluating the in-vitro degradability of the obtained PGSCC material, wherein the test method is a PBS solution soaking method. The PGSCC disc samples (diameter 8mm, thickness 1 mm) were placed in PBS (pH =7.4,5 ml) solution, shaken at 37 ℃ and 100rpm for a certain period of time, the samples were removed, washed and dried, and then the mass loss and the pH of the soak solution were measured, as shown in fig. 7, and as a result, the PGSCC was degraded under in vitro conditions, and as the incubation time increased, the mass of the PGSCC samples decreased continuously, and the pH of the soak solution decreased gradually.

Example 3

(1) Dissolving the PGSCC prepolymer obtained in example 2 and poly-L-lactic acid (PLLA, jinandai handle, eta =1.6 gl/g) in hexafluoroisopropanol (Darrier chemistry, purity is greater than or equal to 97%) to prepare a spinning solution, such as PLLA (1 g) + PGSCC (1 g) + hexafluoroisopropanol (10 ml), and obtaining PGSCC/PLLA composite nanofibers through an electrostatic spinning technology at a receiving distance of 15cm under the process parameters of 10kV voltage and 1ml/h advancing rate, and then curing the nanofibers under the conditions of 100Pa and 80 ℃ for 60 hours as described in example 2;

(2) Obtaining pure PLLA nanofibers by the same method and spinning parameters;

(3) Treating the same PLLA/PGSCC composite nanofiber sample by using Rhodamine B with amino and FITC with maleimide respectively, and modifying the sample by using two fluorescent dyes simultaneously; the PLLA nanofibers were also treated the same;

(4) Two types of nanofiber samples of PLLA/PGSCC and PLLA were observed under a fluorescence microscope, and the two types of fibers were observed under excitation of blue light and green light, respectively, as shown in FIG. 5, it can be seen that the PLLA/PGSCC nanofibers, after being treated identically with two types of fluorescent dyes, were green under excitation of blue light and red under excitation of green light; the PLLA nanofibers do not develop color under blue light or green light excitation and cannot be observed.

Comparative example 1

(1) Adding 0.1mol of sebacic acid (national drug, AR) and 0.1mol of glycerol (national drug, AR) into a 250ml two-neck flask, stirring for 0.5h at the temperature of 140 ℃ under the protection of nitrogen, completely melting the monomers, and forming a clear and transparent liquid by the system;

(2) The temperature is reduced to 120 ℃, and the stirring reaction is carried out for 24 hours;

(3) Reducing the pressure to 3325Pa at 120 ℃, and stirring for reaction for 48 hours to obtain a prepolymer;

(4) The prepolymer was cured at 100Pa at 120 ℃ for 60 hours to give a cured polyester elastomer (PGS).

Claims

1. A polyester elastomer material having the structure shown below,

wherein n is not less than 1,R = H or-COCH ₂ -or-CH ₂ -。

2. The polyester elastomer material according to claim 1, wherein the polyester elastomer is obtained by a melt condensation reaction of a raw material containing sebacic acid, glycerol, citric acid, and L-cysteine.

3. A method for preparing the polyester elastomer material of claim 1, comprising:

mixing sebacic acid, glycerol, citric acid and L-cysteine, melting under protective gas, carrying out esterification reaction under normal pressure, then carrying out reaction under vacuum condition to obtain prepolymer, and curing to obtain the polyester elastomer material.

4. The method according to claim 3, wherein the molar ratio of sebacic acid to glycerol is 1; the molar ratio of sebacic acid to citric acid is 1:0.001-0.6; the molar ratio of sebacic acid to L-cysteine is 1.

5. The method according to claim 3, wherein the protective gas has a melting temperature of 120 to 200 ℃; the protective gas is one or more of nitrogen, argon and helium.

6. The method according to claim 3, wherein a catalyst is added after the melting; the catalyst is one of stannous octoate, stannous chloride, stannous octoate/p-toluenesulfonic acid and stannous chloride/p-toluenesulfonic acid.

7. The process according to claim 3, wherein the esterification reaction is carried out at a temperature of 120 to 200 ℃ for 0.01 to 20 hours.

8. The preparation method according to claim 3, wherein the reaction under vacuum condition is: the reaction temperature is 100-220 ℃, the vacuum degree of the reaction system is 0.1-6000Pa, and the reaction time is 0.5-50h; the prepolymer is purified.

9. The method according to claim 3, wherein the curing is: the temperature is 50-180 ℃, the vacuum degree in the curing process is 0.1-6000Pa, and the curing time is 4-200h.