CN111658819A - Triblock hydrogel copolymer with temperature response and preparation method thereof - Google Patents

Abstract

The invention provides a triblock hydrogel copolymer with temperature response and a preparation method thereof, wherein the hydrogel copolymer is an ABA type triblock reticular copolymer formed by polymerizing a polyethylene glycol monomer and an N-isopropyl acrylamide monomer, the copolymer comprises a mussel bionic tissue adhesive group and a silver nanoparticle anchoring group, and the number average molecular weight of the polyethylene glycol is 3000-5000. The hydrogel copolymer provided by the invention can be used for rapid healing of burn wounds, has biological tissue adhesiveness and antibacterial property, can be used for carrying different medicines according to clinical requirements, has a temperature-sensitive characteristic, is convenient to store and transport, and is beneficial to surgical use such as spraying or injection. The molecular structural formula of the hydrogel copolymer is shown as the formula (I):

Description

Triblock hydrogel copolymer with temperature response and preparation method thereof

Technical Field

The invention belongs to the technical field of hydrogel materials, and particularly relates to a triblock hydrogel copolymer with temperature response and a preparation method thereof.

Background

Burn is a kind of tissue damage caused by various heat sources including hot liquid, high temperature gas, flame, hot metal, chemical substances, etc., and mainly occurs in superficial body tissues such as skin and mucosa. After a severe burn has occurred, in addition to regional local damage to the skin mucosa, the following reactions occur: increased metabolism, decreased body temperature, excessive loss of water, massive loss of proteins, and disturbances of the endocrine and immune systems. The exposed burn wound can cause body fluid balance disorder and defense barrier damage in a short time, and the wound which is not healed for a long time can also become a hotbed for bacteria to colonize and grow. Therefore, after the burn occurs, particularly in large-area burn, the dressing is used for covering the wound surface and is temporarily used as a body surface protection barrier to prevent further invasion of bacteria and promote the wound surface to heal, which is very important.

At present, the traditional medical dressing which is clinically used for burn wounds is mainly gauze and cotton pads, has water absorption and certain air permeability, and is simple in manufacturing process, low in price and reusable. However, the traditional dressing has poor moisturizing effect, does not have antibacterial capability, and can shift and fall off; when the wound dressing is replaced, the gauze is dried and knotted, and granulation tissues are adhered to the wound surface, so that secondary injuries such as pain, bleeding and the like of a patient are caused. How to promote the regeneration and repair of deep local tissues of burn wounds through medical dressings gradually draws attention of clinicians. It has been found that suitable tissue regeneration conditions include certain humidity, temperature and sterility conditions. Therefore, the ideal dressing should have the characteristics of absorbing wound seepage, maintaining the humidity and temperature of the wound, having certain air permeability and antibacterial capability and the like, thereby promoting the healing of the wound.

Synthetic materials have long been found to help promote healing of skin wounds. In 1962, the international paper published by the Winter doctor of university in london in Nature journal, which demonstrates the healing effect of moist environment on wound surface: compared with the sealing of the porcine fault skin defect wound with a polyethylene film, the re-epithelialization probability of the wound exposed to air is increased by 50% (Nature.1962; 193: 293-4). Pulat et al (Polymer edition.2013; 24(7):807-819) synthesizes a novel wound dressing-semipermeable network hydrogel by using ethylene glycol dimethacrylate as a cross-linking agent and polyacrylamide and chitosan as raw materials, so as to realize the burst release of antibiotics and the controlled release of growth factors. The water content of the gel is very high (about 80%), and the swelling property is stable in the pH range (pH4.0-7.0) of the wound matrix; the material is loaded with antibiotic piperacillin-tazobactam, and the growth factor is EGF; when the dressing is applied to the wound surface for 1h, the concentration of the piperacillin-tazobactam in the serum can reach the treatment amount, and the EGF can be continuously released for 5 days. Choi et al (Journal of biological materials research, 2010; 95(2):564-573) prepared a wound-surface-adhesive temperature-sensitive hydrogel for diabetic ulcer, blending glycidyl methacrylate esterified chitosan oligosaccharide, diacryloyl pluronic and rhEGF to prepare a physically crosslinked hydrogel, and irradiating by light to prepare a chemically crosslinked gel; applying 80 mu L of physical cross-linked gel (containing 1 mu g of rhEGF) in a solution state on the burn wound surface of the back of the mouse, irradiating for 30s to enable the physical cross-linked gel to generate chemical cross-linking, and then covering with a medical bandage; research results show that the rhEGF-encapsulated hydrogel can improve the local rhEGF concentration of the wound surface and maintain the differentiation of keratin cells, thereby promoting the healing of the wound surface difficult to heal. In the above series of studies, hydrogel was one of the main active ingredients. As a high molecular polymer, the performance of the hydrogel is superior to that of the traditional dressing and biological dressing, the hydrophilic group enables the hydrogel to have strong water absorption capacity, after water absorption, the hydrogel expands, is firmly combined with water molecules and is stored, and the hydrogel can absorb wound seepage and has certain moisture retention capacity. The three-dimensional network structure formed by the hydrogel macromolecules through crosslinking enables the hydrogel macromolecules to be a carrier of certain specific medicines besides the inherent characteristics of the hydrogel macromolecules, and the hydrogel macromolecules can play the functions of the medicines. On the other hand, various researches show that the organic components of the hydrogel have the capability of improving the microenvironment of the wound surface and can effectively promote the healing of the wound surface.

However, hydrogels also have a number of deficiencies. For example, after the hydrogel is placed on a wound surface, the movement of body muscles easily causes the damage and even the rupture of the gel, thereby increasing the infection risk, and simultaneously destroying the hydrogel structure and affecting the function. In addition, the hydrogel itself is not antimicrobial and does not resist the invasion of bacteria, thus presenting the risk of infection. After the hydrogel is used for a long time, the hydrogel swells due to strong water absorption capacity and is poorly attached to a wound surface. In addition, the ideal hydrogel agent applied to burn wounds needs to meet higher requirements: the damage of the dressing is automatically repaired, and the dressing has the strain; the drug is carried partially, so that the wound surface infection is prevented, and the antibacterial property is achieved; the state can be changed, and the long-time laminating property is realized; releasing certain medicine for promoting wound healing; however, no hydrogel which can achieve the above characteristics together is available in clinic.

Therefore, whether the hydrogel can be produced by a polymerization method or not can automatically repair the damage of the dressing on the basis of ensuring the water absorption and the moisture retention, and has the adaptability; the drug is carried partially, so that the wound surface infection is prevented, and the antibacterial property is achieved; the state can be changed, and the long-time laminating property is realized; at the same time, certain medicine for promoting wound healing is released; this has become a considerable technical problem. In addition, the preparation of hydrogel with the above properties, and whether to prepare a novel hydrogel material with temperature-sensitive characteristics and self-repairing properties, is a technical problem to be solved in the present invention.

Disclosure of Invention

The present invention is directed to solving the above problems, and provides a triblock hydrogel copolymer having a temperature response and a method for preparing the same. The hydrogel copolymer provided by the invention can be used for rapid healing of burn wounds, has biological tissue adhesiveness and antibacterial property, can be used for carrying different medicines according to clinical requirements, has a temperature-sensitive characteristic, is convenient to store and transport, and is beneficial to surgical use such as spraying or injection.

One of the purposes of the invention is to provide a triblock hydrogel copolymer with temperature response, which is an ABA type triblock network copolymer polymerized by polyethylene glycol monomer and N-isopropyl acrylamide monomer, wherein the copolymer comprises mussel bionic tissue adhesive groups and silver nanoparticle anchoring groups, and the number average molecular weight of the polyethylene glycol is 3000-5000; the molecular structural formula of the copolymer is shown as the formula (I):

wherein x, y and z are integers from 1 to n.

Wherein, the mussel bionic tissue adhesive group is dopamine group, and the silver nanoparticle anchoring group is sulfhydryl group. The mass ratio of the polyethylene glycol monomer to the N-isopropyl acrylamide monomer is 1-2: 2-3.

The structure of the hydrogel copolymer provided by the invention has the following characteristics:

1) the hydrogel material contains temperature-sensitive response groups, can endow hydrogel with good temperature response performance, is in a liquid state at normal temperature or below body temperature, is converted into a gel state at body temperature or when contacting body surfaces, is convenient for storage and transportation, and is beneficial to surgical use such as spraying or injection;

2) mussel bionic tissue adhesive group (dopamine group) has been proved to endow the prepared adhesive with good adhesion to biological tissues, and the introduction of the group can ensure good adhesion of hydrogel to burned tissues in the using process;

3) the introduction of the nano-particle anchoring group (sulfydryl) can lead the hydrogel and the silver nano-particles to be combined by organic dynamic bonds, further improve the strength of the silver nano-particle composite hydrogel and simultaneously have good antibacterial property. Under the condition of low temperature, the hydrogel, CsA (cyclosporine A) and silver nanoparticles are prepared into aqueous solution with proper concentration according to the requirements of experimental conditions, and the aqueous solution can be sprayed or injected to burn wounds to form a hydrogel protective layer through the temperature change of the wounds.

The hydrogel material provided by the invention has the characteristics of high strain, biocompatibility, adhesiveness, heat sensitivity, injectability, antimicrobial property and the like. The hydrogel can realize effective sol-gel transformation at low temperature or room temperature, the performance endows the material with good injectability and cleaning convenience after operation, and simultaneously, as the main component in the hydrogel is a high molecular material with good biocompatibility, such as polyethylene oxide (PEG), the hydrogel material is ensured to have excellent biocompatibility to cells.

The hydrogel disclosed by the invention can enable burn wounds to be always under the antibacterial and CsA administration effects through a slow release effect. In addition, because the hydrogel has catechol hydrogen bonds, pi-pi interaction force and dynamic hydrosulfur-silver bonds, the hydrogel material has good self-repairing performance, and the performance can ensure that the wound can be self-repaired when damaged by external force to avoid the injury caused by the exposure of the wound.

The hydrogel prepared by the invention has good self-repairing performance, has excellent antibacterial effect on common E-coli bacteria, is obviously anti-sticking and self-cleaning to skin cells, is convenient to use due to the temperature responsiveness, and can be injected. The mechanical strength of the hydrogel material can be adjusted by changing the content of dopamine and the proportion of other components in the mussel bionic polymer material.

The hydrogel material provided by the invention has an obvious healing promoting effect on burn wounds, wherein after CsA and silver particles are loaded, the CsA is locally released, so that the healing of the burn wounds is promoted, and the local inflammatory reaction intensity of the burn wounds is reduced. Research shows that the hydrogel material of the invention can promote the healing speed of the full-thickness burn wound, reduce the release of inflammatory factors in vivo, promote the growth of granulation tissues and the like.

Another object of the present invention is to provide a method for preparing the triblock hydrogel copolymer having a temperature response, the method comprising the steps of:

(1) firstly, synthesizing a copolymer from an N-isopropyl acrylamide monomer and a polyethylene glycol monomer by using a RAFT (reversible addition-fragmentation chain transfer) polymerization method;

(2) then, replacing the active ester in the copolymer obtained in the step (1) with a mussel bionic tissue adhesive group, and introducing the mussel bionic tissue adhesive group into the polymer;

(3) adding mercaptoethylamine into the product obtained in the step (2) to carry out chemical grafting reaction, thereby obtaining the target product hydrogel copolymer.

Compared with the prior art, the invention has the following beneficial effects:

the hydrogel prepared by the invention has self-repairing capability, antimicrobial property and antifouling property, can be well used as a dressing for healing burn wounds, has obvious temperature-sensitive characteristic, is in a liquid state at normal temperature or below body temperature, is converted into a gel state at body temperature or when contacting body surfaces, is convenient to store and transport, and is beneficial to surgical use such as spraying or injection. The hydrogel copolymer loaded with the CsA and the silver nanoparticles can enable burn wounds to be always under the antibacterial and CsA administration effects through slow release, and can have good self-repairing performance, so that the wounds can be self-repaired due to external force damage to avoid damage caused by exposure of the wounds. Meanwhile, the hydrogel can promote the healing speed of the full-thickness burn wound, reduce the release of inflammatory factors in vivo, promote the growth of granulation tissues and the like.

Drawings

FIG. 1 is a schematic structural view of a hydrogel of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the following embodiments, and it should be noted that the following embodiments are only for explaining and illustrating the present invention and are not intended to limit the present invention. The invention is not limited to the embodiments described above, but rather, may be modified within the scope of the invention.

Example 1

A triblock hydrogel copolymer with temperature response is an ABA type triblock network copolymer polymerized by polyethylene glycol monomers and N-isopropyl acrylamide monomers, the copolymer comprises mussel bionic tissue adhesive groups and silver nanoparticle anchoring groups, and the molecular structural formula is as follows:

the hydrogel copolymer has obvious temperature-sensitive characteristic (as shown in figure 1), is in a liquid state at normal temperature or below body temperature, is converted into a gel state at body temperature or when contacting body surfaces, is convenient to store and transport, and is beneficial to surgical use such as spraying or injection.

The preparation method of the hydrogel refers to ACS applied materials & interfaces, 2017; 9221-9225 ", the method specifically comprises:

(1) firstly, synthesizing a copolymer from an N-isopropyl acrylamide monomer and a polyethylene glycol monomer by using a RAFT (reversible addition-fragmentation chain transfer) polymerization method; adding a cross-linking agent methylene bisacrylamide, an initiator ammonium persulfate and a catalyst dithiocarbamate in the polymerization reaction process;

(2) then, replacing the active ester in the copolymer obtained in the step (1) with a mussel bionic tissue adhesive group, and introducing the mussel bionic tissue adhesive group into the polymer;

(3) adding mercaptoethylamine into the product obtained in the step (2) to carry out chemical grafting reaction, thereby obtaining the target product hydrogel copolymer.

Wherein the number average molecular weight of the polyethylene glycol is 3000-5000, and the mass ratio of the polyethylene glycol monomer to the N-isopropylacrylamide monomer is 1-2: 2-3.

Experimental example 1

A rat severe burn model is constructed, the hydrogel material obtained in example 1 (taking the mass ratio of the polyethylene glycol monomer to the N-isopropylacrylamide monomer as an example, the mass average molecular weight of polyethylene glycol is 3000) is used for repairing after burn, the protective effect of the hydrogel material obtained in example 1 on the local tissue recovery of rats after burn and the inhibition effect of systemic inflammatory response are discussed, and the method is as follows:

40 rats were divided into 4 groups, Control group (Control), model group (Burn), positive Control group (Burn + Intrasite Gel), and experimental group (Burn + hydrogel). All rats were shaved on the back, general anesthetized with 1% sodium pentobarbital 1mL, and the area was 30% of the total surface area (TBSA-K W0.5, K-0.9, W is mouse body weight) was taken as the burn area. All rats except the control group were anesthetized and then scalded in 99 ℃ water for 15 seconds, and the control group rats were anesthetized and then incubated in 37 ℃ water for 15 seconds.

Wound surface was treated 1d after burn. In the experimental group, the wound surface is treated by the novel CsA-carrying hydrogel dressing; in the positive control group, the wound surface is treated by QINGDEJIA (Intrasite Gel, a clinical common hydrogel dressing); the model group was not dosed and the remaining treatments were consistent. After the rat is anesthetized, the back is cleaned and disinfected by chlorhexidine, the drug is administered according to grouping conditions, the administration thickness is 3-5 mm, and the drug is prevented from falling off. At 3, 7, 10 and 14d after the burn, the healing process of the wound surface is measured and recorded by adopting Image Pro Plus software, the area of the scab surface, the healing rate of the wound surface and the complete healing time are calculated, and the morphological change of the wound surface is observed.

The statistical experimental results are shown in table 1:

TABLE 1

Experimental example 2

"ACS applied materials & interfaces.2017; 9221-9225 "the hydrogel prepared in the rat model of severe burn was used as the positive control group 2, and the results are shown in table 2 by loading CsA compared with the experimental group of the present invention:

TABLE 2

Experimental example 3

At 3, 7, 10 and 14d after the burn, tail vein blood collection is adopted, 4 groups of rat blood are respectively taken at each time point, serum is obtained by centrifugation, and IL-6 and TNF-alpha levels are detected by using a Varioskan Flash multifunctional enzyme-linked immunosorbent assay and an ELISA kit.

The results obtained are shown in tables 3 and 4:

TABLE 3

TABLE 4

Meanwhile, wound tissues are taken 14 days after burn, and structural tissue change, collagen distribution and EFG-2 expression conditions among wound granulation tissues are respectively detected.

The experimental results show that the novel CsA-carrying hydrogel dressing can play roles in promoting the healing of the full-thickness burn wound, improving the healing speed, reducing the release of inflammatory factors in vivo, promoting the growth of endothelial cells and the like.

Claims (8)

1. A triblock hydrogel copolymer with temperature response is characterized in that the hydrogel copolymer is an ABA type triblock network copolymer formed by polymerizing polyethylene glycol monomers and N-isopropyl acrylamide monomers, the copolymer comprises mussel bionic tissue adhesive groups and silver nanoparticle anchoring groups, and the number average molecular weight of the polyethylene glycol is 3000-5000; the molecular structural formula of the copolymer is shown as the formula (I):

wherein x, y and z are integers from 1 to n.

2. The temperature-responsive triblock hydrogel copolymer of claim 1, wherein the mussel biomimetic tissue adhesive groups are dopamine groups.

3. The temperature-responsive triblock hydrogel copolymer of claim 1, wherein the nanoparticle anchoring group is a thiol group.

4. The triblock hydrogel copolymer with temperature response according to claim 1, wherein the mass ratio of the polyethylene glycol monomer to the N-isopropylacrylamide monomer is 1-2: 2-3.

5. The temperature-responsive triblock hydrogel copolymer of claim 1 wherein the hydrogel copolymer is in a liquid state at ambient or below body temperature and is converted to a gel state at body temperature or upon contact with a body surface.

6. A method for preparing a triblock hydrogel copolymer having a temperature response according to any one of claims 1 to 5, comprising the steps of:

(1) firstly, synthesizing a copolymer from an N-isopropyl acrylamide monomer and a polyethylene glycol monomer by using a RAFT (reversible addition-fragmentation chain transfer) polymerization method;

(2) then, replacing the active ester group in the copolymer obtained in the step (1) with a mussel bionic tissue adhesive group, and introducing the mussel bionic tissue adhesive group into the polymer;

(3) adding mercaptoethylamine into the product obtained in the step (2) to carry out chemical grafting reaction, thereby obtaining the target product hydrogel copolymer.

7. The method of claim 6, wherein the synthesizing of the copolymer in step (1) further comprises adding a crosslinking agent, an initiator, and a catalyst.

8. The method of claim 7, wherein the cross-linking agent is methylene bisacrylamide, the initiator is ammonium persulfate, and the catalyst is dithiocarbamate.

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