Disclosure of Invention
The invention provides a preparation method of a halloysite and arginine modified polyester urea-urethane composite material, aiming at overcoming the defects and shortcomings of the prior art. The composite material prepared by the method has certain hydrophilicity and bioactivity, good cell compatibility, capability of supporting cell adhesion, growth and proliferation, inducing osteogenic differentiation of stem cells and promoting bone regeneration and repair, biodegradability and capability of being finally degraded along with the generation of new bones.
It is another object of the present invention to provide a composite material prepared by the above method.
It is a further object of the present invention to provide the use of the above composite material.
The purpose of the invention is realized by the following technical scheme:
a preparation method of a halloysite and arginine modified polyester urea-urethane composite material comprises the following steps:
1) under the conditions of inert atmosphere and stirring, carrying out prepolymerization reaction on polycaprolactone diol and hexamethylene diisocyanate under the action of an initiator, cooling to 40-70 ℃, adding an L-arginine-1, 8-octanediol ester solution, continuously reacting for 5-10 h, diluting, dialyzing, and freeze-drying to obtain a polyester urea-urethane material; the molar ratio of the hexamethylene diisocyanate to the polycaprolactone diol is (1.2-2) to 1; the temperature of the prepolymerization reaction is 60-90 ℃, and the time of the prepolymerization reaction is 0.5-2 h;
2) dissolving the polyester urea-urethane material in an organic solvent, adding the halloysite nanotube, uniformly dispersing, and forming a film to obtain the composite material.
The initiator in the step 1) is stannous octoate or tin isooctanoate; the dosage of the initiator is 0.01-0.05 percent of the total mass of the polycaprolactone diol and the hexamethylene diisocyanate.
The L-arginine-1, 8-octanediol ester solution in the step 1) is obtained by dissolving L-arginine-1, 8-octanediol ester in an organic solvent; the organic solvent is dimethyl sulfoxide (DMSO) or N, N-dimethylformamide DMF; the L-arginine-1, 8-octanediol ester: the molar volume ratio of the organic solvent is 0.25 mol: (400-500) mL;
the number average molecular weight of the polycaprolactone diol in the step 1) is 500-3000, preferably 530-2000;
the rotating speed of stirring in the step 1) is 100-300 r/min; in the step 1), the molar ratio of the L-arginine-1, 8-octanediol ester to the polycaprolactone diol PCL is (0.2-1): 1;
the dilution in the step 1) refers to diluting the reaction solution by DMSO, and the dialysis refers to dialyzing in a dialysis bag with a molecular weight cutoff of 3500;
the polycaprolactone diol is dried in vacuum before use.
The organic solvent in the step 2) is dichloromethane, dimethyl sulfoxide DMSO, and N, N-dimethylformamide DMF; the usage amount of the halloysite nanotube accounts for 2-10% of the total mass of the composite material, and is preferably 6%.
The water contact angle of the polyester urea urethane film material is 50-80 degrees. The Zeta potential on the surface of the polyester urea urethane membrane material shows positive electricity in a wide range of pH <10, the positive electricity is increased along with the increase of the dosage of L-arginine-1, 8-octanediol ester, the pH is 7.0 to 7.0, and the Zeta potential is 33mV to 90 mV.
The halloysite nanotube in the step 2) has the diameter of 30-70 nm and the length of 300 nm-3 mu m.
The elastic modulus of the composite material is 2-24 MPa, and the tensile strength is 0.6-10 MPa.
The composite material is applied to bone tissue engineering materials.
The bone tissue engineering material is a bone filling material, a biomedical material for bone repair or a biomedical material for bone regeneration.
The polyester urea urethane material, namely the arginine modified polyester urea urethane, has the following chemical structure:
in the formula I, the molar ratio of the arginine diol ester chain segment b to the PCL chain segment a is 0.2-1: 1.
compared with the prior art, the invention has the following advantages and beneficial effects:
1. compared with the traditional polyurethane material, the arginine modified polyester urea urethane material based on halloysite and arginine prepared by the invention has the advantages of no cytotoxicity and good cell compatibility, and can promote the deposition of collagen, support the growth of cells and promote the proliferation of cells.
2. The chain extender used in the invention is L-arginine-1, 8-octandiol ester, isocyanate is aliphatic hexamethylene diisocyanate, the medical polymer material PCL chain segment approved by FDA is selected as the soft segment, the degradation product is nontoxic and absorbable, and the degradation product arginine is also beneficial to wound repair and reduces inflammatory reaction. The electropositivity and the degradability of the material can be controlled by controlling the proportion of chain extender arginine diol ester, the interaction of the material and water can be enhanced by an arginine chain segment, the hydrophilicity of the material is improved, and the problem that the actual degradation rate of PCL type polyurethane is too slow is solved.
3. The halloysite nanotube with high length-diameter ratio is used as a composite material to further enhance the mechanical property of the material and enhance the capability of the material for inducing the osteogenic differentiation of stem cells, and the prepared composite material has good physical and chemical properties and biological properties, can promote the generation of new bones and the repair of bone defects and realize self degradation, is easy to process and prepare into a bone repair scaffold and is used for repairing bone injuries clinically.
Detailed Description
The invention is further illustrated by the following specific examples. The following examples are preferred embodiments of the present invention, but are not intended to limit the scope of the present invention in any manner.
Polycaprolactone (PCL) diol (CAS:36890-68-3, Sigma, 189405 Mn-530; Sigma, 189421 Mn-2000).
EXAMPLE 1 preparation of arginine-modified polyester Urea urethane
The preparation method of the arginine modified polyester urea urethane based on polycaprolactone, hexamethylene isocyanate and arginine diol ester comprises the following steps:
(1) freeze-drying L-arginine-1, 8-octanediol ester for 72h, dissolving with dimethyl sulfoxide, dissolving every 0.25mol of L-arginine-1, 8-octanediol ester to 400mL of dimethyl sulfoxide, and adding a molecular sieve for later use to obtain an L-arginine-1, 8-octanediol ester solution;
(2) vacuumizing Polycaprolactone (PCL) diol (Mn-530) to remove water for 3h, heating to 70 ℃ under the protection of inert gas (nitrogen), mechanically stirring at the stirring speed of 150r/min, adding Hexamethylene Diisocyanate (HDI) (the molar ratio of HDI to PCL diol is 1.2:1, 1.6:1, 2.0: 1), dropwise adding tin isooctanoate (prepared into 0.5mg/mL initiator solution by using toluene) accounting for 0.05 percent of the total mass of PCL and HDI after uniform stirring, and carrying out prepolymerization for 1 h; after the pre-coalescence is finished, the reaction temperature is reduced to 60 ℃, L-arginine-1, 8-octanediol ester solution (the molar ratio of L-arginine-1, 8-octanediol ester to PCL diol is 0.2:1,0.6:1,1:1) is dripped for chain extension, the reaction is continued for 8 hours, DMSO is added to dilute the reaction solution (the mass-to-volume ratio of HDI, PCL and L-arginine-1, 8-octanediol ester to the solvent in the reaction solution is (5-10) g:100mL), after dialysis is carried out in a dialysis bag with molecular weight cut-off of 3500, freezing and drying are carried out at-20 ℃ for 72 hours, and then polyester urea urethane materials PEUU0.2, PEUU0.6 and PEUU1.0 are obtained, and the specific formula is shown in Table 1.
The polyester urea polyurethane material obtained was dissolved in methylene chloride, 10mL of methylene chloride was added per 1g of the material, and cast into a film in a 5 cm. times.5 cm or 10 cm. times.10 cm polytetrafluoroethylene mold. The arginine modified polyester urea urethane prepared by the invention is easy to cast into a membrane.
Wherein, after L-arginine and 1, 8-octanediol are subjected to dehydration condensation under the protection of p-toluenesulfonic acid, the obtained product is subjected to pH adjustment to 9.5 to remove a protecting group, and CO is introduced2Neutralizing, filtering, and freeze drying.
Preparation of polyurethane (comparative):
vacuumizing Polycaprolactone (PCL) diol (Mn-530) to remove water for 3h, heating to 70 ℃ under the protection of inert gas (nitrogen), mechanically stirring at the stirring speed of 150r/min, adding Hexamethylene Diisocyanate (HDI) (the molar ratio of HDI to PCL diol is 1.2: 1), dropwise adding tin isooctanoate (prepared by toluene into an initiator solution of 0.5 mg/mL) accounting for 0.05 percent of the total mass of PCL and HDI after uniform stirring, and carrying out prepolymerization for 1 h; after the pre-coalescence is finished, the reaction temperature is reduced to 60 ℃,1, 4-butanediol is dripped for chain extension (the molar ratio of the 1, 4-butanediol to the PCL diol is 0.2:1), DMSO is added twice in the reaction process, products in the reaction process are fully dissolved to prevent implosion, the reaction is continued for 8 hours, and after dialysis is carried out in a dialysis bag with the molecular weight cutoff of 3500, the polyurethane material PU-BDO is obtained after freezing and drying at the temperature of-20 ℃ for 72 hours. The formulation of the polyurethane material PU-BDO is shown in Table 1.
10mL of DMF is added into every 1g of polyurethane material PU-BDO to be dissolved, and the solution is cast into a film in a polytetrafluoroethylene mold with the thickness of 5cm multiplied by 5cm or 10cm multiplied by 10 cm.
TABLE 1 polyester urea urethane materials and polyurethane formulations
HDI is hexamethylene diisocyanate, PCL530 is Polycaprolactone (PCL) diol (Mn-530), L-Arg-8 is L-arginine-1, 8-octandiol ester, BDO is 1, 4-butanediol.
Compared with the arginine modified polyester urea urethane (PEUU0.2, PEUU0.6 and PEUU1.0), the polyurethane PU-BDO has the advantages of very slow material degradation, strong hydrophobicity, difficult cell adhesion and difficult use as a bone repair material.
EXAMPLE 2 preparation of polyester Urea urethanes with different molecular weights PCL
In this example, PCLs with molecular weights of 530 and 2000 were used to prepare polyesterurea urethanes respectively, and the preparation procedure and reaction conditions were the same as those of example 1. The formulation of this example is shown in Table 2.
TABLE 2 formulation of polyester urea urethane materials
HDI is hexamethylene diisocyanate, PCL530 is Polycaprolactone (PCL) diol (Mn-530), PCL2000 is polycaprolactone diol (Mn-2000), and L-Arg-8 is L-arginine-1, 8-octandiol ester.
In the prepared polyester urea urethanes, the material prepared from PCL2000 is less in arginine mass and is hydrophobic. Compared with the material prepared from PCL2000, the material prepared from PCL530 is more hydrophilic, the material prepared from PCL530 has the advantages that the water contact angle is continuously reduced along with the increase of the ratio n (molar ratio) of arginine alcohol ester to PCL, the electropositivity of the membrane surface is gradually enhanced, the mechanical property of the material with n equal to 1.0 is poorer, the material with soft segment of PCL530 and the material with the material feeding ratio n equal to 0.2 and n equal to 0.6 has better mechanical property, and is more suitable for the adhesion and growth of cells.
Example 3 preparation of halloysite nanotubes and arginine-modified polyester urea urethane composites
The polyester urea urethane PEUU0.2 prepared in the example 1 is dissolved in dichloromethane, different amounts of halloysite nanotubes (the halloysite nanotubes account for 2%, 4%, 6%, 8% and 10% of the total mass of the composite material) are respectively added, stirred and dispersed, and due to the positive charge characteristic of the polyester urea urethane and the negative charge characteristic of the outer tube wall of the halloysite, the halloysite nanotubes can be easily and uniformly dispersed in the solution without sedimentation, and are cast into a film, and then cut into a composite patch (namely the composite material) with the diameter of 5mm by a punch.
Compared with polyester urea urethane without halloysite, the composite material (polyester urea urethane material compounded by halloysite nanotubes) of the embodiment has slightly enhanced hydrophilicity and mechanical properties, has no obvious difference in surface Zeta potential and degradability when the pH is 7, can also support cell growth, has the best bone defect repairing effect of the halloysite nanotube composite polyester urea urethane patch added with 6% halloysite, and shows that a large amount of new bones are generated in the defect center of a rat skull defect repairing result of 2 months.
And (3) performance testing:
(1) hydrophilicity test:
the polyester urea urethane material of example 1 and the polyurethane were subjected to the hydrophilicity test, and the test results are shown in table 3.
TABLE 3 Water contact Angle of the polyester Urea urethane materials and polyurethanes
As can be seen from table 3, the hydrophilicity of the arginine-modified polyester urea urethane was significantly improved compared to the polyurethane PU-BDO.
(2) Mechanical Property test
The polyester urea urethane film material (PEUU0.2, PEUU0.6) in example 1 was subjected to mechanical property test, and the test results are shown in FIG. 1. FIG. 1 is a stress-strain curve of the polyester urea urethane film material (PEUU0.2, PEUU0.6) in example 1. As can be seen from FIG. 1, the polyester urea urethane prepared by the invention has good mechanical properties and good elasticity.
(3) The polyester urea urethane film materials (PEUU0.2, PEUU0.6 and PEUU1.0) and polyurethane (PU-BDO) in example 1 were subjected to Zeta potential performance tests, and the test results are shown in FIG. 2.
FIG. 2 is a surface Zeta potential curve of the polyester urea urethane (PEUU0.2, PEUU0.6, PEUU1.0) and the polyurethane film material (PU-BDO) in example 1. As can be seen from fig. 2, the Zeta potential on the membrane surface shows that the arginine-modified polyester urea urethane material (i.e., polyester urea urethane) exhibits stable electropositivity, and the potential increases with increasing arginine alcohol ester content.
(4) The polyurethane (PU-BDO), the polyester urea urethane material PEUU not compounded in example 1 (i.e. PEUU 0.2) and the compounded film material in example 3 (PEUU-HNT, the content of halloysite is 6%, the molar ratio of HDI: PCL530: L-Arg-8 is 1.2:1.0:0.2) were subjected to bone cell culture tests, and the test results are shown in FIG. 3.
FIG. 3 shows fluorescence images of Calcein-AM/PI dead cells staining for 1,4 and 7 days of polyurethane (PU-BDO), polyester urea urethane material PEUU not compounded in example 1 (i.e., PEUU 0.2), and composite membrane material in example 3 (PEUU-HNT, halloysite content is 6%, and molar ratio of HDI: PCL530: L-Arg-8 is 1.2:1.0: 0.2).
As can be seen from FIG. 3, when the uncomplexed polyester urea urethane material of example 1 and the composite membrane material of example 3 were inoculated with bone cells and cultured for 1,4, 7 days for dying and then observed under an inverted fluorescence microscope, it was found that the bone cells were completely spread, the material could support cell growth and proliferation, and the statistical result of the number of living cells showed that the material had the effect of promoting cell proliferation.
In addition, when the molar ratio of the arginine diol ester to the PCL is 0.2-0.6, the material is more beneficial to cell growth, spreading and proliferation.
(5) In vivo experiments
(5-1) construction of skull defect model: SPF SD rat is anesthetized by intraperitoneal injection with 3% sodium pentobarbital, head hair is removed, surface skin is cleaned, skin and subcutaneous tissue are cut, 2 bone defect models with 5mm bilateral symmetry are manufactured on rat skull by bone drill after periosteum is stripped. The composite patch (polyester urea urethane material not compounded in example 1 and composite film material in example 3) was implanted at the bone defect, sutured, and the wound site was sterilized with iodophor. The physiological condition of the patient is recorded by regular observation after the operation. The rats in the experimental group were sacrificed by carbon dioxide asphyxiation in months 1, 2, and 3, the skull was removed, the peripheral blood was washed with physiological saline, the obtained bone tissue sample was subjected to CT scanning and histological analysis after being fixed with 4% paraformaldehyde for 48 hours, and the effect of the patch on the skull defect repair was evaluated. The test results are shown in FIGS. 4 to 6.
FIG. 4 is Micro-CT images of bone tissues 2 months after the uncomplexed polyester urea urethane material (PEUU 0.2) in example 1 and the complexed film material (PEUU-HNT, 6% halloysite, HDI: PCL530: L-Arg-8 molar ratio of 1.2:1.0:0.2) in example 3 were implanted into the skull defect site of a rat; wherein, no patch is blank group, uncomplexed polyester urea urethane PEUU is PEUU0.2 in the embodiment 1, and PEUU-HNT is the composite material with 6 percent of halloysite in the embodiment 3;
FIG. 5 is a H & E staining graph of a bone tissue section 2 months after the uncomplexed polyester urea urethane material (PEUU 0.2) of example 1 and the complexed film material (PEUU-HNT, 6% halloysite, HDI: PCL530: L-Arg-8 molar ratio of 1.2:1.0:0.2) of example 3 were implanted into a skull defect site of a rat; wherein, no patch is blank group, uncomplexed polyester urea urethane PEUU is PEUU0.2 in the embodiment 1, and PEUU-HNT is the composite material with 6 percent of halloysite in the embodiment 3;
FIG. 6 is Masson staining graph of a bone tissue section 2 months after the uncomplexed polyester urea urethane material (PEUU 0.2) of example 1 and the complexed film material (PEUU-HNT, 6% halloysite, HDI: PCL530: L-Arg-8 molar ratio of 1.2:1.0:0.2) of example 3 were implanted into a skull defect site of a rat; in the figure, NB represents new bone tissue; wherein, no patch is blank group, the polyester urea urethane PEUU which is not compounded is PEUU0.2 in the embodiment 1, and the PEUU-HNT is the composite material with 6 percent of halloysite in the embodiment 3.
(5-2) results:
as shown in fig. 4, fig. 5 and fig. 6, relative to the blank defect, the PEUU patch (PEUU0.2, PEUU-HNT) is implanted with the surrounding collagen deposition, and a part of new bones are generated at the edge of the rat skull defect of the group of the rat skull implant polyester urea urethane patch, the positively charged patch may play a role in adsorbing collagen and protein, recruiting cells and supporting cell growth, while the PU-BDO is easy to slide due to strong hydrophobic effect and is difficult to fix to the defect as the patch material.
(6) Structural characterization of materials
FIG. 7 is an SEM image of the cross section of the polyester urea urethane material (PEUU 0.2) which is not compounded in example 1 and the composite film material (PEUU-HNT, the content of halloysite is 6%, and the molar ratio of HDI: PCL530: L-Arg-8 is 1.2:1.0:0.2) in example 3; FIG. a shows the uncomplexed polyester urea urethane material (PEUU 0.2) of example 1, and FIG. b shows the material of the composite film of example 3.
The above examples of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.