阅读说明：本技术 一种pH响应型水凝胶生物载体及应用 (pH response type hydrogel biological carrier and application ) 是由 赵兴卉 翟俊辉 杜红 王轲珑 于 2021-11-03 设计创作，主要内容包括：本发明公开了一种pH响应型水凝胶生物载体,所述pH响应型水凝胶生物载体由透明质酸钠与甲基丙烯酸酐在光引发剂存在的条件下,用365nm紫外激光照射,透明质酸钠侧链上的羟基通过光致交联经过酯化作用聚合而成透明质酸的甲基丙烯酸酯衍生物。本发明还公开了一种装载有治疗性蛋白PDGF-BB的pH响应型水凝胶生物载体。本发明采用原位自由基聚合的方法合成,反应条件温和,对PDGF-BB的生物活性不会产生影响；把PDGF-BB包裹在水凝胶内,避免暴露在酶环境中,提高了PDGF-BB生物活性的稳定性。(The invention discloses a pH response type hydrogel biological carrier, which is prepared by irradiating sodium hyaluronate and methacrylic anhydride with 365nm ultraviolet laser in the presence of a photoinitiator, and polymerizing hydroxyl on a sodium hyaluronate side chain through photocrosslinking and esterification to obtain a methacrylate derivative of hyaluronic acid. The invention also discloses a pH response type hydrogel biological carrier loaded with the therapeutic protein PDGF-BB. The invention adopts the method of in-situ free radical polymerization for synthesis, has mild reaction conditions, and does not influence the biological activity of PDGF-BB; PDGF-BB is wrapped in the hydrogel, so that exposure to an enzyme environment is avoided, and the stability of the biological activity of the PDGF-BB is improved.)

1. The pH response type hydrogel biological carrier is characterized by being prepared by irradiating methacrylic acid hyaluronic acid with 365nm ultraviolet laser to initiate a crosslinking reaction in the presence of a photoinitiator and a crosslinking agent.

2. The pH-responsive hydrogel biovector of claim 1, wherein the photoinitiator is I2959 and the cross-linking agents are first cross-linking agent GDMA and second cross-linking agent AI 102.

3. The pH-responsive hydrogel biovector of claim 1, wherein the methacrylated hyaluronic acid is prepared from sodium hyaluronate and methacrylic anhydride in a molar ratio of 1: 30 is synthesized by esterification.

4. The pH-responsive hydrogel biovector of claim 2, wherein the molar ratio of the first crosslinking agent GDMA to the second crosslinking agent AI102 is (1-4): (0-2).

5. The method for preparing a pH-responsive hydrogel biovector of any one of claims 1 to 3, which comprises irradiating methacrylated hyaluronic acid with 365nm ultraviolet laser in the presence of a photoinitiator, a first crosslinking agent GDMA and a second crosslinking agent AI102 to initiate a crosslinking reaction.

6. A pH-responsive hydrogel biovector loaded with a therapeutic protein according to any one of claims 1 to 3, wherein the pH-responsive hydrogel biovector loaded with the therapeutic protein is prepared by lyophilizing the hydrogel biovector and loading the therapeutic protein in the pH-responsive hydrogel biovector by a dry immersion method.

7. The therapeutic protein loaded pH-responsive hydrogel biovector of claim 6, wherein the therapeutic protein is platelet-derived growth factor.

8. The therapeutic protein-loaded pH-responsive hydrogel biovector of claim 7, wherein the platelet-derived growth factor is in the form of BB-type dimer.

9. The method for preparing a pH-responsive hydrogel biovector loaded with a therapeutic protein as claimed in any one of claims 6 to 8, which comprises the steps of lyophilizing the hydrogel biovector and loading the therapeutic protein in the pH-responsive hydrogel biovector by a dry immersion method.

10. Use of the therapeutic protein loaded pH-responsive hydrogel biovector of any one of claims 6-8 in the preparation of a medicament for promoting wound repair and tissue regeneration.

Technical Field

The invention discloses a hydrogel biological carrier, and belongs to the technical field of pharmacy.

Background

Platelet-derived growth factor (PDGF) is a cationic glycoprotein that is heat-resistant, acid-resistant, and easily hydrolyzed by proteases, and can be secreted by a variety of cells, such as: platelets, fibroblasts, macrophages, and the like. PDGF has four monomers, PDGF-A, PDGF-B, PDGF-C and PDGF-D, which are linked by disulfide bonds to form a dimer. Among them, the dimeric form of PDGF-B, PDGF-BB, acts as a mitotic promoter, stimulating fibroblast and smooth muscle cell proliferation and migration, and promoting macrophage production and secretion of growth factors. The effect on wound repair, tissue regeneration bone and tooth regeneration and joint repair is more remarkable. Particularly in wound repair, is the only growth factor approved by the U.S. Food and Drug Administration (FDA) for the treatment of diabetic ulcers.

The diseases of wound repair and tissue regeneration require growth factors to maintain a certain concentration at the diseased part for a long time, but PDGF-BB has short half-life (< 2 min) and is easily degraded by protease, and like a large amount of protease exists in a chronic wound bed, PDGF-BB is easily inactivated. Multiple bolus doses are typically used to maintain drug concentration, but this presents a risk of tumorigenesis. There is therefore a need in the art for a carrier that can both increase PDGF-BB stability and at the same time maintain a certain drug concentration over a long period of time to ensure safety and efficacy of PDGF administration.

Disclosure of Invention

Based on the technical problems in the prior art, the invention aims to provide a hydrogel biological carrier, which can improve the stability of PDGF-BB in pharmacodynamic action by controllably releasing the bioactivity of PDGF-BB and ensure the biological safety of the drug use through the degradation of the carrier.

The invention comprehensively considers the biocompatibility of methacrylic anhydridized hyaluronic acid hydrogel and the characteristic of protecting the slow release of growth factors, and prepares the growth factor-combined pH response type hydrogel biological carrier by introducing PDGF-BB into the methacrylic anhydridized hyaluronic acid hydrogel network, aiming at improving the biocompatibility, pH response, cell slice layer detachment and protection of the traditional hydrogel, and the characteristics of slowly releasing the growth factors.

In view of the above, the present invention provides a pH-responsive hydrogel bio-carrier, which is prepared by irradiating a methacrylated hyaluronic acid with 365nm ultraviolet laser in the presence of a photoinitiator and a cross-linking agent to initiate a cross-linking reaction.

In a preferred technical scheme, the photoinitiator is I2959, and the crosslinking agents are a first crosslinking agent GDMA and a second crosslinking agent AI 102.

In another preferred embodiment, the methacrylated hyaluronic acid is prepared from sodium hyaluronate and methacrylic anhydride in a molar ratio of 1: 30 is synthesized by esterification.

In a preferred technical scheme, the molar ratio of the first crosslinking agent GDMA to the second crosslinking agent AI102 is (1-4): (0-2).

Secondly, the invention provides a preparation method of the pH response type hydrogel bio-carrier, which comprises the step of irradiating 365nm ultraviolet laser to initiate a crosslinking reaction of methacrylated hyaluronic acid in the presence of a photoinitiator, a first crosslinking agent GDMA and a second crosslinking agent AI 102.

In a third aspect, the present invention provides the above pH-responsive hydrogel biovector loaded with a therapeutic protein, wherein the pH-responsive hydrogel biovector loaded with the therapeutic protein is prepared by lyophilizing the hydrogel biovector and loading the therapeutic protein in the pH-responsive hydrogel biovector by a dry immersion method.

In a preferred embodiment, the therapeutic protein is platelet-derived growth factor.

In a more preferred embodiment, the platelet-derived growth factor is in the form of a BB-type dimer.

In a fourth aspect, the present invention provides a method for preparing the above pH-responsive hydrogel biovector loaded with a therapeutic protein, the method comprising the steps of lyophilizing the hydrogel biovector, and loading the therapeutic protein in the pH-responsive hydrogel biovector by a dry immersion method.

Finally, the invention provides application of the pH response type hydrogel biological carrier loaded with the therapeutic protein in preparation of medicines for promoting wound repair and tissue regeneration.

The pH response type hydrogel biological carrier is synthesized by adopting an in-situ free radical polymerization method, and the therapeutic protein is loaded in the pH response type hydrogel biological carrier by using a dry state soaking method, so that the reaction condition is mild, and the biological activity of PDGF-BB cannot be influenced; PDGF-BB is wrapped in hydrogel, so that exposure to an enzyme environment is avoided, and stability is improved. The release of PDGF-BB is realized by the degradation of hydrogel, and the invention selects two crosslinking agents responding to the degradation of alkaline pH value: the first crosslinking agent GDMA and the second crosslinking agent AI102, the degradation of the two crosslinking agents is based on self ester bond groups, but the degradation rates of the two crosslinking agents are different under alkaline conditions. The pH response type hydrogel biological carrier provided by the invention can control the gel degradation speed by controlling the compatibility proportion according to different wound types, namely different pH values of wound parts, so as to adapt to application requirements. Considering that the pH value of the wound part of a human body is about 8.0, the two cross-linking agents have different degradation speeds at 8.0, and the second cross-linking agent has better water solubility than the first cross-linking agent and relatively more ester bonds, so the second cross-linking agent has a higher degradation rate than the first cross-linking agent. By adjusting the ratio of the two, for example GDMA: the AI102 ratio is 1: 2, the release rate is the slowest, which provides control of the ratio between the two cross-linking agents to achieve different rates of hydrogel degradation. The appropriate crosslinker ratio can be selected for treatment of different diseases and wound types (see figure 1).

Drawings

FIG. 1: schematic illustration of controlled release PDGF-BB pH responsive hydrogel preparation;

FIG. 2: m-HA¹H-NMR spectrum;

FIG. 3: a real picture of a pH responsive hydrogel for controlled release of PDGF-BB;

FIG. 4: testing the compression performance of the pH responsive hydrogel with different cross-linking agent ratios;

FIG. 5: scanning electron micrographs of pH-responsive hydrogels with different crosslinker ratios;

FIG. 6: a graph of swelling ratios of pH responsive hydrogels at different crosslinker ratios;

FIG. 7: a graph of cumulative PDGF-BB release rates from pH-responsive hydrogels at different crosslinker ratios;

FIG. 8: a pH responsive hydrogel cytotoxicity assay;

FIG. 9: a histogram of migration of pH-responsive hydrogels on 3T3 cells;

FIG. 10 is a graph showing the migration effect of pH-responsive hydrogel on 3T3 cells;

FIG. 11 is a graph showing the healing of wounds on the whole skin of mice treated by different treatment methods;

FIG. 12 is a graph of the area of the wounds on the whole skin of mice in different treatment modes as a function of time.

Detailed Description

The invention will be further described with reference to specific embodiments, and the advantages and features of the invention will become apparent as the description proceeds. These examples are only illustrative and do not limit the scope of protection defined by the claims of the present invention.

Example 1 preparation of pH-responsive hydrogel biovectors

FIG. 1 shows a schematic diagram of the preparation of a PDGF-BB pH-responsive hydrogel, wherein A is methacrylic anhydride, B is sodium hyaluronate, 1 is a first crosslinker GDMA, and 2 is a second crosslinker AI 102. The preparation steps are specifically described below.

1. Preparation of methacrylated hyaluronic acid (m-HA)

Sodium Hyaluronate (HA) and Methacrylic Anhydride (MA) are esterified to synthesize methacrylate derivatives of hyaluronic acid, and the method comprises the following steps:

(1) 2g of sodium Hyaluronate (HA) powder was weighed, dissolved in 100mL of deionized water, and stirred overnight in a refrigerator at 4 ℃ to dissolve the powder sufficiently.

(2) The pH of the HA solution was adjusted by adding 5mol/L sodium hydroxide to maintain the pH of the reaction between 8 and 9, followed by slowly adding 1.6mL of methacrylic anhydride dropwise to the HA solution and continuously stirring the reaction at 4 ℃ for 24 hours.

(3) Subsequently, m-HA was precipitated in excess acetone, washed with ethanol, and then dissolved in 50ml of deionized water.

(4) Dialyzing with deionized water for 48 hours in a dialysis bag with molecular weight cut-off of 14000Da to remove unreacted methacrylic anhydride and other by-products to obtain purified m-HA, which is lyophilized for further use.

Dissolving m-HA with deuterated water as a solvent, wherein the concentration is 6mg/ml, and carrying out nuclear magnetic characterization, wherein a nuclear magnetic diagram of the m-HA is shown in figure 2. From¹The H-NMR spectrum showed D at delta 4.79ppm₂A characteristic peak of O; delta 3-4ppm is the characteristic peak of proton hydrogen in the HA ring structure; delta 1.86ppm is the characteristic peak of H on the methyl group in HA; delta.2.03 ppm is the characteristic peak for methyl H on the side chain N-acetylglucosamine. Compared with HA nuclear magnetic spectrum, two new peaks of m-HA at delta 5.68ppm and delta 6.13ppm are characteristic peaks of olefin protons in methacrylic anhydride, and can indicate that the methacrylic anhydride is successfully grafted into the HA molecular structure.

2. preparation of pH response type hydrogel biological carrier

Preparation of platelet-derived growth factor-loaded m-HA hydrogels

Taking m-HA as a monomer, GDMA (glyceryl dimethacrylate, a first cross-linking agent) and AI102 (polylactic acid-polyethylene glycol-polylactic acid acrylate, a second cross-linking agent) as cross-linking agents, adding an initiator I2959 (2-hydroxy-4' - (2-hydroxyethoxy) -2-methyl propiophenone), initiating a reaction at 365nm of ultraviolet light, preparing a pH response type hydrogel biological carrier, and then freezing and drying the pH response type hydrogel biological carrier.

The method comprises the following specific steps:

preparing methacrylic acid hyaluronic acid and a second cross-linking agent AI102 into an aqueous solution; respectively adding DMSO into a first cross-linking agent GDMA and an initiator I2959 to prepare solutions;

and (3) uniformly mixing the m-HA, the AI102 aqueous solution, the I2959 solution and the GDMA solution in a reaction tube, and reacting for 2min under 365nm ultraviolet light to form the pH response type hydrogel biological carrier. After lyophilization, PDGF-BB is loaded onto the hydrogel.

Wherein the first crosslinking agent GDMA: the molar ratio of the second cross-linking agent AI102 is (1-4) to (0-2);

(1) solution preparation:

taking 20mg of freeze-dried m-HA, adding 1ml of deionized water to prepare a solution of 20 mg/ml;

adding 500 μ l of deionized water into AI 10250 mg to obtain 100mg/ml solution;

taking 250mg of GDMA, adding 500 mul of DMSO, and preparing 500mg/ml solution;

taking I2959100 mg, adding DMSO1ml to prepare a solution of 100 mg/ml.

(2) Preparation of hydrogels with different crosslinker ratios:

TABLE 1 hydrogel Synthesis parameters (crosslinker ratio GDMA: AI 102)

And (3) uniformly mixing the m-HA, the AI102 aqueous solution, the I2959 solution and the GDMA solution in a reaction tube, and reacting for 2min under 365nm ultraviolet light to obtain the hydrogel with different proportions.

FIG. 3 is a schematic representation of a pH responsive hydrogel for controlled release of PDGF-BB. The results of the pH-responsive hydrogel compression performance test with different crosslinker ratios are shown in fig. 4. The young's modulus increases significantly with increasing amount of cross-linker. The larger the young's modulus, the less likely the material is to deform. The greater the amount of crosslinker under the same compressive strain, the higher the stress required for the hydrogel and the greater the compressive modulus. From the results, when GDMA: AI102= 4: young's modulus is the largest at 1, indicating the smallest deformation under stress.

3. PDGF-BB loading of pH-responsive hydrogel biovectors

PDGF-BB (purchased from military medical academy of sciences) is loaded in a pH-responsive hydrogel biological carrier by using a dry state soaking method, namely, after the hydrogel is completely lyophilized, the PDGF-BB is soaked in a PDGF-BB solution, so that the PDGF-BB is sufficiently loaded on the hydrogel. The reaction is complete to form a hydrogel comprising PDGF-BB.

The method comprises the following specific steps:

the hydrogel was punched out with a punch to make a cylinder with a diameter of 15mm and a height of 8mm, then the hydrogel was lyophilized for 3 days, after which the lyophilized hydrogel was soaked in 5ml of a solution containing PDGF-BB with a concentration of 50ng/ml for 48h to ensure sufficient absorption of the hydrogel, and then washed 3 times with PBS to wash away PDGF-BB not bound to the hydrogel, to prepare a growth factor-bound hydrogel bio-carrier.

Example 2 characterization of platelet-derived growth factor-loaded m-HA hydrogels

1. Hydrogel topography characterization

And (3) placing the hydrogel sample which reaches the equilibrium swelling in a freeze dryer at-50 ℃ for freeze drying for 48h, freezing and brittle-breaking the obtained sample in liquid nitrogen, spraying gold to prepare a sample, and observing the cross section appearance of the sample by using a Scanning Electron Microscope (SEM). Figure 5 is a scanning electron microscope image of pH-responsive hydrogels with different crosslinker ratios. It can be seen that the larger the proportion of crosslinking agent, the smaller the pore size, indicating a higher degree of crosslinking. When the molar ratio of GDMA to AI102 is 1: 2, the degree of crosslinking is maximal.

2. Swelling ratio characterization of hydrogels

And (4) carrying out swelling performance test by using the hydrogel scaffold after freeze drying. The hydrogel sample was punched with a punch to make a cylinder having a diameter of 1.5cm and a height of 12mm, and then the sample was lyophilized. The original weight W of each hydrogel group was weighed and recorded using an analytical balance₀Then, the hydrogel was soaked in 10mL of PBS buffer solution, and the swelling change of the hydrogel was observed, and samples were taken at 2 h, 6h, 12 h, 24 h, 48h and 72 h, respectively. Carefully remove the water from the hydrogel surface with filter paper, weigh and record the weight Wi of the hydrogel samples, set at least 3 replicates per sample, and average the final results. Swelling ratio (W) of hydrogelThe following formula can be used for calculation:

swelling ratio (W) ═ W (Wi-W)₀ )/W₀×100％

As shown in fig. 6, when GDMA: the AI102 ratio is 1: at 0, the swelling ratio is the greatest. When the ratio of the two is 4: at 1, the swelling ratio was minimal. The swelling degree of the hydrogel support is increased sharply in the first 14 h, and particularly, the two hydrogels with small addition of the cross-linking agent are mainly characterized in that the addition of the cross-linking agent is small, the cross-linking degree is low, the formed polymer network is relatively sparse, and a large amount of water can be absorbed. The hydrogel scaffold is soaked for about 24 hours to reach swelling balance.

3. Characterization of pH-responsive hydrogel release kinetics for different crosslinker ratios

Dried HA-MA hydrogels loaded with different crosslinker ratios of PDGF-BB were placed in PBS buffer pH =8 and incubated in a 37 ℃ water bath for controlled drug release studies. At the specified time (1, 2, 3, 4, 5, 7, 10 days) 200. mu.L of the release medium was removed and 200. mu.L of neat PBS buffer was added. The collected release solution was assayed for the amount of PDGF-BB released by enzyme-linked immunosorbent assay (ELISA).

A graph of the cumulative PDGF-BB release rates from pH-responsive hydrogels at different crosslinker ratios is shown in FIG. 7. When the ratio of GDMA: the AI102 ratio is 1: at 0, the release rate is fastest. When the ratio of the two is 1: at 2, the release rate is slowest.

4. Characterization of pH-responsive hydrogel biocompatibility

Cytotoxicity test:

adding appropriate amount of prepared hydrogel without PDGF-BB and hydrogel containing PDGF-BB into 24-well plate, adding appropriate amount of culture medium containing only P/S (pH =8), incubating for 24 h in incubator, taking out culture medium, and filtering with 0.22 μm filter membrane. 1X 10 inoculation per well⁴Single cell, 37 ℃, 5% CO₂Incubate under conditions overnight. Adding the leaching solution, then continuing to incubate for 24 h, and then using a CCK-8 kit to verify whether the hydrogel is cytotoxic or not. First crosslinking agent of the hydrogel used: the ratio of the second crosslinking agent is 1: 2.

the results of the pH-responsive hydrogel cytotoxicity experiments are shown in fig. 8. The biological activity of the hydrogel coating PDGF-BB at different concentrations is more than 75%, so that the prepared hydrogel is considered to have good biocompatibility.

5. Migration of 3T3 cells by pH-responsive hydrogels

(1) Serum-free DMEM medium (pH =8) preparation: 0.5 ml of diabody was taken and then 49.5 ml of DMEM high sugar medium was added.

(2) The ruler and the marker pen were placed on a super clean bench and subjected to UV sterilization for 30 min, then DMEM complete medium, 1 XPBS were placed in a 37 ℃ water bath and incubated for 20 min, and pancreatin was incubated at room temperature.

(3) Plate paving: a6-hole plate is taken, and 5 transverse lines of through holes are drawn on the back of the plate by using marks. Cells were diluted to 5X 10⁴2 ml of seed per well. 37 ℃ and 5% CO₂Incubate under conditions to allow the bottom of the well plate to be filled with a single layer.

(4) In order to eliminate the effect of complete medium on the results of promoting cell proliferation and migration, the medium was changed to P/S only medium 12 h before the application. A10 μ L tip was used to scribe a line perpendicular to the line. Old medium was removed and washed 3 times with 1 × PBS to remove the streaked cells.

(5) The PDGF-free hydrogel and PDGF-BB-containing hydrogel were soaked in serum-free DMEM medium. 2 ml of the above extract was added to each well. A blank set (P/S only medium) was set. After sample addition, the mixture was incubated in an incubator at 37 ℃ with 5% CO 2. The cell mobility was calculated by taking 0, 12, 24, 36 and 48h photographs of the cells in the same visual field, and calculating the area using Image J software.

FIG. 9 is a statistical plot of the migration of pH-responsive hydrogels on 3T3 cells; fig. 10 is a graph showing the observation of the migration effect of the pH-responsive hydrogel on 3T3 cells. First crosslinking agent of the hydrogel used: the ratio of the second crosslinking agent is 1: 2. 3T3 cells constantly migrated toward the center and the area of the scratch was significantly reduced compared to the hydrogel-only control group using cells affected with both uncoated PDGF-BB and hydrogel-coated PDGF-BB. The wound area is quantified through ImageJ, and the cell migration rate of the hydrogel without the PDGF-BB coating can reach 37% in 36h, the cell migration rate of the hydrogel coating the PDGF-BB can reach 42% in 36h, and the cell migration rate of a control group is only about 10%. This demonstrates that the PDGF-BB-encapsulated hydrogel can promote migration of 3T3 cells, and may have a promoting effect on wound healing.

6. Mouse full-thickness skin wound healing experiment:

mice were divided into three groups, a PDGF-BB free hydrogel and a PDGF-BB containing hydrogel. First crosslinking agent of the hydrogel used: the ratio of the second crosslinking agent is 1: 2. drug loaded hydrogel was injected in situ to the wound site (pH =8) and subsequently covered with a non-adhesive sterile patch and fixed with a 3M patch. Mice wounds were photographed at different time points (0, 3, 7, 10, 14 days) using a ruler as a reference. Wound area was calculated using Image J software.

Wound closure rate% = (S)₀-S_N）/S₀×100

Wherein S is₀Is the initial wound area, S_NIs the area of wound surface in N days

FIG. 11 is a graphical representation of the healing of wounds on the full-thickness skin of mice treated with different treatments. It can be seen from figure 11 that the wounds of the diabetic mice were all shrinking, but the hydrogel-encapsulated PDGF-BB group had more significant wound healing than the other two groups. The time-dependent curves of the wound area of the mice in fig. 12 show that at 7 d, the average wound area of the 3 groups was 83.4%, 72.8% and 65.0%, respectively; at 14 d, the average wound area of the 3 groups became 54.9, 25.1% and 7.8%, and the hydrogel-coated PDGF-BB group was most reduced in wound area compared with the other two groups, and thus it could be seen that the hydrogel-coated PDGF-BB group was advantageous for wound healing.