阅读说明：本技术 一种含盐立构复合型聚乳酸温敏性水凝胶及其制备方法 (Saline stereo-structure composite polylactic acid temperature-sensitive hydrogel and preparation method thereof ) 是由 包建娜 陈世昌 陈文兴 张先明 毛海良 于 2021-01-26 设计创作，主要内容包括：本发明涉及温敏性水凝胶领域,公开了一种含盐立构复合型聚乳酸温敏性水凝胶及其制备方法。该温敏性水凝胶按重量份计包括以下原料：1～20份组分A,1～20份组分B,60～98份盐溶液；所述组分A为聚左旋乳酸-聚乙二醇-聚左旋乳酸(PLLA-PEG-PLLA)三嵌段共聚物,所述组分B为聚右旋乳酸-聚乙二醇-聚右旋乳酸(PDLA-PEG-PDLA)三嵌段共聚物。在本发明的温敏性水凝胶中,通过改变盐的种类和浓度即可改变水凝胶的溶胶-凝胶相转变温度和力学性能,可控性好,且制备过程简单。(The invention relates to the field of temperature-sensitive hydrogel, and discloses salt-containing stereo-composite polylactic acid temperature-sensitive hydrogel and a preparation method thereof. The temperature-sensitive hydrogel comprises the following raw materials in parts by weight: 1-20 parts of component A, 1-20 parts of component B and 60-98 parts of salt solution; the component A is a poly-L-lactic acid-polyethylene glycol-poly-L-lactic acid (PLLA-PEG-PLLA) triblock copolymer, and the component B is a poly-D-lactic acid-polyethylene glycol-poly-D-lactic acid (PDLA-PEG-PDLA) triblock copolymer. In the temperature-sensitive hydrogel, the sol-gel phase transition temperature and the mechanical property of the hydrogel can be changed by changing the type and the concentration of the salt, and the temperature-sensitive hydrogel has good controllability and simple preparation process.)

1. A saline stereo-structure composite polylactic acid temperature-sensitive hydrogel is characterized by comprising the following raw materials in parts by weight: 1-20 parts of component A, 1-20 parts of component B and 60-98 parts of salt solution; the component A is a poly-L-lactic acid-polyethylene glycol-poly-L-lactic acid triblock copolymer, and the component B is a poly-D-lactic acid-polyethylene glycol-poly-D-lactic acid triblock copolymer; the concentration of the salt solution is 0.01-10 wt%; the solute in the salt solution is at least one of metal halide salt or metal sulfate.

2. The temperature-sensitive hydrogel according to claim 1, wherein the solute in the salt solution is at least one of sodium chloride, magnesium chloride, sodium sulfate, and magnesium sulfate.

3. The temperature-sensitive hydrogel according to claim 1, wherein the salt solution has a concentration of 0.5 to 3 wt%.

4. The temperature-sensitive hydrogel according to claim 1, wherein in the component A or the component B, the number average molecular weight of the polyethylene glycol block is 500 to 5000, and the number average molecular weight of a single poly-L-lactic acid or poly-D-lactic acid block is 500 to 2000.

5. The temperature-sensitive hydrogel according to claim 1 or 4, wherein said component A or component B is prepared by the following method: and (2) taking the polyethylene glycol terminated by the hydroxyl at the two ends as an initiator and stannous octoate as a catalyst, respectively taking L-lactide or D-lactide as a monomer, carrying out ring-opening polymerization reaction, and separating out a reaction product to obtain the component A or the component B.

6. A method for preparing a temperature-sensitive hydrogel according to any one of claims 1 to 5, comprising the steps of:

(1) respectively dissolving the component A and the component B in a salt solution to prepare a component A solution and a component B solution;

(2) mixing the component A solution and the component B solution to prepare a mixed solution;

(3) and heating the mixed solution to form gel, thereby obtaining the saline stereo-structure composite polylactic acid temperature-sensitive hydrogel.

7. The method according to claim 6, wherein in the step (1), the mass fraction of the component A in the component A solution is 1-20 wt%; in the component B solution, the mass fraction of the component B is 1-20 wt%.

8. The method according to claim 6 or 7, wherein in the step (2), the mass ratio of the component A solution to the component B solution is 1: 9-9: 1.

9. The method according to claim 6, wherein in the step (3), the temperature rise is performed by the following specific process: the temperature is raised by 1-5 ℃ every time, and the temperature is maintained for 5-30 min every time.

10. The method according to claim 6 or 9, wherein in the step (3), the initial temperature of the temperature rise is 0 to 5 ℃.

Technical Field

The invention relates to the field of temperature-sensitive hydrogel, in particular to saline stereo composite polylactic acid temperature-sensitive hydrogel and a preparation method thereof.

Background

The temperature-sensitive hydrogel is a novel biomedical material, is concerned about and has wide application prospect in the fields of drug release, tissue engineering and the like. The amphiphilic block copolymer has a hydrophobic-hydrophilic balance characteristic, forms micelles by self-assembly in an aqueous solution, can generate sol-gel phase transition only by raising the temperature, and is an excellent injectable hydrogel material. However, designing and developing a hydrogel material with excellent properties such as biocompatibility, biodegradability, mechanical properties and phase transition behavior is still a very challenging task, and the breakthrough of the technology has a very important significance for promoting the application of the material.

The aliphatic polyester thermo-sensitive hydrogel is widely concerned in the industry due to biocompatibility and biodegradability. The enantiomer of polylactic acid (PLA), polylactic acid (PLLA), and poly-d-lactic acid (PDLA) can undergo stereocomplex crystallization between their molecular chains. In aqueous solutions of amphiphilic PLLA-polyethylene glycol (PEG) -PLLA and PDLA-PEG-PDLA triblock copolymer blends, PLLA/PDLA stereocomplex crystals can drive physical gelation of aqueous solutions (e.g., Fujiwara T et al, Macromol. biosci., 2001, 1, 204-. When PLLA-PEG-PLLA and PDLA-PEG-PDLA aqueous solutions are blended at a ratio of 1: 1, a solution-gel transition may be exhibited with temperature changes. Compared with the traditional polyester temperature-sensitive hydrogel, the stereo composite crystallization improves the interaction and association degree between the hydrophobic chain segments of the corresponding physical gel, accelerates the gelation, and can realize the effective improvement of the mechanical property.

However, the hydrogels of PLLA-PEG-PLLA/PDLA-PEG-PDLA still have some disadvantages, and the methods for regulating the temperature response behavior and mechanical properties of the stereo-composite hydrogels reported at present are to design complex topology (Nagahama K et al, Polymer, 2007, 48, 2649-. The method relates to complex chemical synthesis, and the hydrogel preparation process is relatively complex, and has strict condition requirements and poor controllability.

Disclosure of Invention

In order to solve the technical problems, the invention provides a saline stereo-structure composite polylactic acid temperature-sensitive hydrogel and a preparation method thereof. The sol-gel phase transition temperature and the mechanical property of the hydrogel can be changed by changing the type and the concentration of the salt, the proportion of the component A, B and the total concentration of the polymer, and the hydrogel has good controllability and simple preparation process.

The specific technical scheme of the invention is as follows:

a saline stereo-structure composite polylactic acid temperature-sensitive hydrogel comprises the following raw materials in parts by weight: 1-20 parts of component A, 1-20 parts of component B and 60-98 parts of salt solution; the component A is a poly-L-lactic acid-polyethylene glycol-poly-L-lactic acid (PLLA-PEG-PLLA) triblock copolymer, and the component B is a poly-D-lactic acid-polyethylene glycol-poly-D-lactic acid (PDLA-PEG-PDLA) triblock copolymer; the concentration of the salt solution is 0.01-10 wt%, and the solute in the salt solution is at least one of metal halide salt or metal sulfate.

On the basis of the existing PLLA-PEG-PLLA/PDLA-PEG-PDLA temperature-sensitive hydrogel, salt is added to form salt/stereocomplex polylactic acid temperature-sensitive hydrogel, the principle that the salt effect and the coordination interaction of water and PEG are utilized to increase the hydrophobicity of micelles in a solution is utilized, and the stereocomplex crystallization and microstructure of a system can be regulated and controlled by regulating the type and concentration of the salt, so that the sol-gel phase transition temperature and the mechanical property of the temperature-sensitive hydrogel are regulated; with the increase of the salt concentration, the sol-gel phase transition temperature is obviously reduced, and the mechanical property is obviously increased.

The temperature-sensitive hydrogel disclosed by the invention keeps better biocompatibility and biodegradability of the PLLA-PEG-PLLA/PDLA-PEG-PDLA hydrogel, can be metabolized by a human body, and can be used in biomedical fields such as drug carriers, tissue engineering and the like. Compared with the prior art that the sol-gel phase transition temperature and the mechanical property of the PLLA-PEG-PLLA/PDLA-PEG-PDLA temperature-sensitive hydrogel are regulated and controlled by changing the internal factors (topological structure, copolymerization composition, molecular weight, distribution and the like), the method can realize the regulation and control by changing the type and concentration of the salt, and has the advantages of simple hydrogel preparation process and good controllability of the sol-gel phase transition temperature and the mechanical property.

Preferably, the solute in the salt solution is at least one of sodium chloride, magnesium chloride, sodium sulfate and magnesium sulfate.

Preferably, the concentration of the salt solution is 0.5-3 wt%.

Preferably, in the component A or the component B, the number average molecular weight of the polyethylene glycol block is 500-5000, and the number average molecular weight of a single poly-L-lactic acid or poly-D-lactic acid block is 500-2000.

Preferably, the preparation method of the component A or the component B is as follows: and (2) taking the polyethylene glycol terminated by the hydroxyl at the two ends as an initiator and stannous octoate as a catalyst, respectively taking L-lactide or D-lactide as a monomer, carrying out ring-opening polymerization reaction, and separating out a reaction product to obtain the component A or the component B.

A method for preparing the temperature-sensitive hydrogel, comprising the steps of:

(1) respectively dissolving the component A and the component B in a salt solution to prepare a component A solution and a component B solution;

(2) mixing the component A solution and the component B solution to prepare a mixed solution;

(3) and heating the mixed solution to form gel, thereby obtaining the saline stereo-structure composite polylactic acid temperature-sensitive hydrogel.

In the above preparation process, the sol-gel phase transition temperature of the temperature-sensitive hydrogel can also be adjusted by adjusting the concentrations of the component A solution and the component B solution in the step (1) and the ratio of the two solutions in the step (2).

Preferably, in the step (1), the mass fraction of the component A in the component A solution is 1-20 wt%; in the component B solution, the mass fraction of the component B is 1-20 wt%.

Preferably, in the step (2), the mass ratio of the component A solution to the component B solution is 1: 9-9: 1.

Preferably, in step (3), the specific process of raising the temperature is as follows: the temperature is raised by 1-5 ℃ every time, and the temperature is maintained for 5-30 min every time.

Preferably, in the step (3), the initial temperature of the temperature rise is 0 to 5 ℃.

Compared with the prior art, the invention has the following advantages:

(1) at present, the regulation and control method for the thermal gelation of the amphiphilic polymer aqueous solution capable of being stereoscopically compounded is complex, harsh in conditions and poor in controllability. The sol-gel phase transition temperature and the mechanical property of the hydrogel can be changed by changing the type and the concentration of the inorganic salt, the proportion of the component A, B and the total concentration of the polymer, the controllability is good, and the preparation process is simple;

(2) the invention regulates and controls the stereo composite crystal and microstructure of the system by the principle of increasing the hydrophobicity of the micelle in the solution through the salt effect and the coordination interaction of water-PEG, and further regulates and controls the sol-gel phase transition temperature of the system.

(3) The hydrogel has good biocompatibility and biodegradability, can be metabolized by a human body, and can be used in biomedical fields such as drug carriers, tissue engineering and the like.

Drawings

FIG. 1 is a wide angle X-ray diffraction pattern measured for example 4 and comparative example 2;

fig. 2 is a graph showing the measured storage modulus and loss modulus as a function of temperature for example 4 and comparative example 2 at room temperature.

Detailed Description

The present invention will be further described with reference to the following examples.

The following examples are presented to enable those skilled in the art to more fully understand the present invention and are not intended to limit the invention in any way. The reagents and medicines used for preparing the hydrogel of the invention are as follows: PEG was purchased from aladdin corporation; lactide was purchased from prasuk corporation for future use; the catalyst stannous octoate was purchased from Sigma; the solvent toluene is the analytical pure of the Chinese medicine, and the water is removed by distilling with metallic sodium for standby.

Example 1

Preparing a saline stereo-structure composite polylactic acid temperature-sensitive hydrogel by the following method, and determining the sol-gel phase transition temperature:

(1) preparation of component A and component B:

the synthesis of component A is described in Bhatia, S.R., et al, Macromolecules, 2007, 40, 7864-7873. Adding double-end hydroxyl-terminated PEG and L-lactide in a molar ratio of 1: 1 into a Hibutack tube, vacuumizing, introducing argon, performing gas replacement for 3 times, and adding dry toluene with the amount of 4 times of the mass of the PEG. Heating to 130 ℃ to azeotropically distill out 1/3 toluene to remove residual moisture in the system, adding stannous octoate, wherein the dosage of the stannous octoate is 0.2 wt% of the mass of the PEG, and reacting for 12 hours. Adding the reaction mixture into an ether/n-hexane (50/50v/v) precipitator according to the volume ratio of 1: 1 for precipitation, performing suction filtration and separation to obtain a solid, namely a component A, and performing vacuum drying for 12 hours at 25 ℃ for later use. The component B is prepared by the same method, and only the L-lactide is changed into the D-lactide.

Product molecular weight by nuclear magnetic resonance (¹H-NMR), and the molecular weight distribution index (PDI) is determined by Gel Permeation Chromatography (GPC), in the following way:

NMR measurement: the block copolymers were tested by NMR (Bruker, 400MHz)¹H NMR spectrum, and further calculating M thereof_n. The test temperature was room temperature, the solvent was deuterated chloroform, and the chemical shift (δ) was corrected by the solvent peak. Molecular weight calculation shows: according to¹M of the block copolymer was calculated from the ratio of the area of the chemical shift peak at δ of 3.6ppm to the area of the chemical shift peak at δ of 1.5ppm on the H-NMR spectrum and the theoretical molecular weight of the PEG segment_nAnd M of polylactic acid block therein_n. Molecular weight distribution test: the molecular weight distribution of the copolymer was measured by GPC (model Waters 1525/2414) at 30 ℃ with tetrahydrofuran as the mobile phase and monodisperse polystyrene as the standard.

The specific structural characteristics of component a and component B prepared in step (1) are shown in table 1.

Table 1: preparation and structural Properties of Components A and B

(2) Preparation of salt solution:

dissolving sodium chloride in deionized water, and uniformly stirring to obtain a salt solution with the concentration of 0.5 wt%.

(3) Preparing saline stereo-structure composite polylactic acid temperature-sensitive hydrogel:

dissolving the component A prepared in the step (1) in the salt solution prepared in the step (2) to obtain a component A solution with the concentration of the component A being 5 wt%; dissolving the component B prepared in the step (1) in the salt solution prepared in the step (2) to obtain a component B solution with the concentration of the component B being 5 wt%; mixing the component A and the component B in equal mass ratio into a bottle, placing the bottle in a water bath, gradually heating the bottle from 5 ℃ to 70 ℃ in steps, heating the bottle at 2 ℃ every time, keeping the temperature constant for 15 minutes at intervals, and then testing whether gel is formed or not by adopting a test tube inversion method. The test tube inversion method is that a sample bottle is inverted in a vertical direction, whether the sample flows within 10 seconds is observed, if the sample does not flow, the sample is considered to be gelled, and if the sample flows, the sample is considered to be a solution.

Examples 2 to 7 and comparative examples 1 to 3

Examples 2 to 7 and comparative examples 1 to 3 differ from example 1 in that the salt solution concentration in step (2), and the component A solution concentration and the component B solution concentration in step (3) were changed according to Table 2, and the remaining preparation processes were the same.

Test example

(1) Sol-gel phase transition temperature:

the concentrations of the component A solution, the component B solution, the salt solution and the mixed sol-gel phase transition temperature in examples 1 to 7 and comparative examples 1 to 3 are shown in Table 2.

Table 2: preparation conditions and Sol-gel phase transition temperatures of examples 1 to 7 and comparative examples 1 to 3

As can be seen from Table 2, the sol-gel phase transition temperature of the hydrogels is influenced by the concentrations of component A and component B and the salt concentration:

first, from comparative examples 1 to 3, it can be seen that: the blending solution with the concentration of the component A solution and the component B solution being 5-11 wt% shows sol-gel phase transition, and the sol-gel phase transition temperature is reduced along with the increase of the concentration of the component A and the component B.

From examples 1 to 3 and comparative example 1, examples 4 to 5 and comparative example 2, and examples 6 to 7 and comparative example 3, it can be seen that: the addition of sodium chloride will lower the sol-gel phase transition temperature of the system and as the concentration of sodium chloride increases, the sol-gel phase transition temperature decreases.

(2) Wide angle X-ray scattering diffractogram:

to further confirm that the sol-gel phase transition temperature of the hydrogel of the present invention is correlated with the stereocomplex crystals between PLLA and PDLA, the hydrogels prepared in example 4 and comparative example 2 were subjected to synchrotron radiation X-ray diffraction analysis using a wavelength of 0.124nm in the light of the upper sea. The results are shown in FIG. 1, in which SC represents a stereocomplex crystal of PLLA/PDLA, and HC represents a homogeneous crystal of PLLA or PDLA. As can be seen from fig. 1: the presence of sodium chloride in the system promotes the formation of stereocomplex crystals between PLLA and PDLA.

(3) Storage modulus and loss modulus change with temperature:

to characterize the mechanical properties of the hydrogels of the present invention, storage modulus (G ') and loss modulus (G') at different temperatures were determined using an RS6000 rheometer (Thermo-Fisher Co., Ltd.) and the results are shown in FIG. 2. As can be seen from fig. 2: the G' value at 60 ℃ is 4.2Pa without addition of sodium chloride; after the sodium chloride is added, the G' value with the concentration of 1 wt% is increased to 15.9Pa, which shows that the mechanical property of the hydrogel can be effectively improved by adding the sodium chloride.

Finally, it should be noted that the above-mentioned list is only a specific embodiment of the present invention. It is obvious that the present invention is not limited to the above embodiments, but many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.