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

A kind of triblock hydrogel copolymer with temperature response and preparation method thereof

technical field

The invention belongs to the technical field of hydrogel materials, in particular to a temperature-responsive triblock hydrogel copolymer and a preparation method thereof.

Background technique

Burn is a kind of tissue damage caused by a variety of heat sources including hydrothermal fluids, high-temperature gases, flames, hot metals, and chemicals. It mainly occurs in surface tissues such as skin and mucous membranes. Opportunity for severe burns, in addition to local skin and mucous membrane local damage, the following reactions will occur: increased metabolism, decreased body temperature, excessive loss of water, massive loss of protein, and disorders of the endocrine and immune systems. The exposed burn wounds will not only cause disturbance of the body's fluid balance and damage to the defense barrier in a short period of time, but also the long-term non-healing wounds will become a breeding ground for bacterial colonization and growth. Therefore, after the occurrence of burns, especially in large-area burns, it is very important to use dressings to cover the wound surface to temporarily serve as a protective barrier on the body surface to prevent further invasion of bacteria and promote wound healing.

At present, most of the traditional medical dressings used clinically for burn wounds are mainly gauze and cotton pads, which have water absorption and certain air permeability. In addition, the traditional medical dressings are simple in production process, inexpensive and reusable. However, the traditional dressings have poor moisturizing effect and do not have antibacterial ability. At the same time, the dressings will shift and fall off. When the wound dressings are replaced, the gauze is dry and the granulation tissue grows and adheres to the wound surface, causing pain, Bleeding and other secondary injuries. How to promote the regeneration and repair of local tissue in deep burn wounds through medical dressings has gradually attracted the attention of clinicians. Existing studies have concluded that a suitable tissue regeneration environment includes certain humidity, temperature and sterile conditions. Therefore, the ideal dressing should have the characteristics of absorbing wound exudate, maintaining the humidity and temperature of the wound, certain air permeability and antibacterial ability, so as to promote wound healing.

Synthetic materials have long been found to help promote healing of skin wounds. In 1962, Dr. Winter of the University of London published a famous paper in the journal Nature, demonstrating the healing effect of moist environment on wounds: the probability of re-epithelialization of air-exposed wounds compared with sealing porcine tomographic skin defect wounds with polyethylene film 50% increase (Nature. 1962; 193:293-4). (Polymer edition. 2013; 24(7): 807-819) synthesized a novel wound dressing- ─Semi-permeable network hydrogels to achieve burst release of antibiotics and controlled release of growth factors. The water content of this gel is very high (about 80%) and the swelling properties are stable in the pH range of the wound matrix (pH 4.0-7.0); and this material is loaded with antibiotics piperacillin-tazobactam, growth factors It is EGF; when the dressing is applied to the wound for 1 hour, the serum piperacillin-tazobactam concentration can reach the therapeutic amount, and the sustained release of EGF can be achieved for 5 days. Choi et al. (Journal of biomedical materials research. 2010; 95(2): 564-573) prepared a wound-adhesive warm hydrogel for diabetic ulcers by esterifying glycidyl methacrylate with chitosan oligosaccharide, dipropylene Physically cross-linked hydrogel was prepared by blending acyl pluronic and rhEGF, and then chemically cross-linked gel was prepared by light irradiation; 80 μL of physical cross-linked gel (containing 1 μg rhEGF) was applied to the back burn wound of mice , 30s of light to make it chemically cross-linked, and then covered with medical bandages; the results show that the hydrogel encapsulating rhEGF can increase the local rhEGF concentration in the wound, maintain the differentiation of keratinocytes, and promote the healing of refractory wounds . In the above series of studies, hydrogel was a major active ingredient. As a high molecular polymer, its performance is better than that of traditional dressings and biological dressings. The hydrophilic group in it makes the hydrogel itself specific and strong water absorption capacity. After water absorption, the hydrogel swells and is firmly combined with water molecules and preserved. , can absorb wound exudate at the same time, has a certain moisturizing ability. The three-dimensional network structure formed by the cross-linking of hydrogel macromolecules makes it, in addition to its own inherent characteristics, also can become the carrier of some specific drugs and exert the function of drugs. On the other hand, various studies have shown that the organic components of hydrogels have the ability to improve the microenvironment of the wound and can effectively promote wound healing.

However, hydrogels also have many shortcomings. For example, after the hydrogel is placed on the wound, the movement of the body muscles can easily lead to damage or even rupture of the colloid, increasing the risk of infection, and also destroying the structure of the hydrogel and affecting its function. In addition, the hydrogel itself is not antibacterial and cannot resist the invasion of bacteria, so there is a risk of infection. After long-term use of the hydrogel, the hydrogel swells due to its strong water absorption capacity, and the adhesion to the wound surface is poor. In addition, the ideal hydrogel applied to burn wounds needs to meet higher requirements: it can automatically repair the damage of the dressing and has adaptability; it carries some drugs to prevent wound infection and has antibacterial properties; the state can be changed, and it has long-term fit. ; release a drug that promotes wound healing, etc.; however, there is currently no hydrogel that can achieve the above characteristics in clinical practice.

Therefore, whether a hydrogel can be produced by means of polymerization, on the basis of ensuring water absorption and moisturizing properties, it can also automatically repair the damage of the dressing, and has flexibility; it can carry some drugs to prevent wound infection and has antibacterial properties; state It can be changed and has a long-term fit; at the same time, it releases a drug that promotes wound healing; this has become a technical problem worthy of study. In addition, in addition to the preparation of hydrogels with the above properties, whether a new type of hydrogel material with temperature-sensitive properties and self-healing can be prepared has become a technical problem to be solved urgently in the present invention.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the above technical problems, and provide a temperature-responsive triblock hydrogel copolymer and a preparation method thereof. The hydrogel copolymer provided by the invention can be used for the rapid healing of burn wounds, has biological tissue adhesion and antibacterial properties, can carry different drugs according to clinical needs, and has temperature-sensitive properties, which is convenient for storage and transportation, And beneficial for surgical use such as spray or injection.

One of the objectives of the present invention is to provide a temperature-responsive triblock hydrogel copolymer, which is an ABA-type triblock polymerized from polyethylene glycol monomer and N-isopropylacrylamide monomer. A segmented network copolymer, the copolymer comprises a mussel biomimetic tissue adhesion group and a silver nanoparticle anchoring group, the polyethylene glycol has a number average molecular weight of 3000-5000; the molecular structure of the copolymer is As shown in formula (I):

Wherein, the x, y, and z are all integers from 1 to n.

Wherein, the mussel biomimetic tissue adhesion group is a dopamine group, and the silver nanoparticle anchoring group is a sulfhydryl group. The mass ratio of the polyethylene glycol monomer to the N-isopropylacrylamide monomer is 1-2:2-3.

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

1) The hydrogel material of the present invention contains a temperature-sensitive responsive group, which can endow the hydrogel with good temperature-responsive performance. It is in a liquid state at room temperature or below body temperature, and changes at body temperature or when it contacts the body surface. In a gel state, it is convenient for storage and transportation, and it is beneficial for surgical use such as spraying or injection;

2) The mussel biomimetic tissue adhesive group (dopamine group) has been proven to endow the prepared adhesive with good adhesion to biological tissues. Good adhesion to burned tissue;

3) Nanoparticle anchoring group (thiol group), the introduction of this group can make organic dynamic bond between the hydrogel and silver nanoparticles, further improve the strength of silver nanoparticle composite hydrogel, and at the same time have good performance. of antibacterial properties. Under low temperature conditions, the hydrogel, CsA (cyclosporine A) and silver nanoparticles were prepared according to the experimental conditions to prepare an aqueous solution with a suitable concentration. The solution can be applied to the burn wound by spraying or injection. The temperature change forms a hydrogel protective layer.

The above-mentioned hydrogel materials provided by the present invention have the characteristics of high strainability, biocompatibility, adhesiveness, heat sensitivity, injectability and antimicrobial properties. The hydrogel can achieve an effective sol-gel transition at low temperature or room temperature, and this performance endows the material with good injectability and ease of postoperative cleaning. At the same time, the main component of the hydrogel is biocompatibility Good polymer materials, such as polyethylene oxide (PEG), ensure that the obtained hydrogel materials have excellent biocompatibility with cells.

The hydrogel of the present invention can keep the burn wound under the effect of antibacterial and CsA administration all the time through the sustained release effect. Moreover, due to the presence of catechol hydrogen bonds, pi-pi interaction force and dynamic mercapto-silver bonds in the hydrogel, the hydrogel material will have good self-healing properties, which can ensure that the wound can be damaged by external forces. Self-healing from damage caused by the nakedness of the wound.

The hydrogel prepared by the invention has good self-healing performance, excellent antibacterial effect on common E-coli bacteria, obvious anti-sticking and self-cleaning to skin cells, and the temperature responsiveness of the hydrogel makes it easy to use , can be carried out by injection. The mechanical strength of the hydrogel material can be adjusted by changing the content of dopamine and the ratio of other components in the mussel biomimetic polymer material.

The above-mentioned hydrogel material provided by the present invention has an obvious effect of promoting the healing of burn wounds. After loading CsA and silver particles, the local release of CsA helps to promote the healing of burn wounds and reduce the intensity of local inflammatory response of burns. Studies have shown that the hydrogel material of the present invention can promote the healing speed of full-thickness burn wounds, reduce the release of inflammatory factors in the body, and promote the growth of granulation tissue.

The second object of the present invention is to provide a preparation method of the above-mentioned temperature-responsive triblock hydrogel copolymer, the preparation method comprising the following steps:

(1) N-isopropylacrylamide monomer and polyethylene glycol monomer are firstly synthesized by RAFT polymerization method;

(2) then replace the active ester in the copolymer obtained in step (1) with the mussel biomimetic tissue adhesive group, and introduce the mussel biomimetic tissue adhesive group into the polymer;

(3) adding mercaptoethylamine to the result of step (2) to carry out chemical grafting reaction to obtain the target product hydrogel copolymer.

Compared with the prior art, the beneficial effects of the present invention are as follows:

The hydrogel prepared by the invention has self-healing ability, anti-microbial property and anti-pollution property, can be well used as a dressing for burn wound healing, and at the same time has obvious temperature-sensitivity characteristics. The liquid state changes to a gel state at body temperature or when it contacts the body surface, which is convenient for storage and transportation, and is beneficial for surgical use such as spraying or injection. The hydrogel copolymer is loaded with CsA and silver nanoparticles, which can keep the burn wound under the action of antibacterial and CsA administration through sustained release, and has good self-healing performance, ensuring that the wound can self-repair when damaged by external force Injury from the nudity of the wound. At the same time, the hydrogel can promote the healing speed of full-thickness burn wounds, reduce the release of inflammatory factors in the body, and promote the growth of granulation tissue.

Description of drawings

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

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the examples. It is necessary to point out that the following examples are only used to explain and illustrate the present invention, and are not intended to limit the present invention. . Some non-essential improvements and adjustments made by those skilled in the art based on the above-mentioned contents of the invention still belong to the protection scope of the present invention.

Example 1

A temperature-responsive tri-block hydrogel copolymer is an ABA-type tri-block network copolymer polymerized from polyethylene glycol monomers and N-isopropylacrylamide monomers, and the The copolymer contains mussel biomimetic tissue adhesion groups and silver nanoparticle anchoring groups, and its molecular structure is as follows:

The hydrogel copolymer has obvious temperature-sensitive properties (as shown in Figure 1), it is in a liquid state at room temperature or below body temperature, and changes into a gel state when it is at body temperature or in contact with the body surface, which is convenient for its Storage and transportation, and beneficial for surgical use such as spray or injection.

The preparation method of the hydrogel refers to the method in "ACS applied materials & interfaces. 2017; 9(11):9221-9225", specifically:

(1) First, the N-isopropylacrylamide monomer and the polyethylene glycol monomer are synthesized by RAFT polymerization method; in the polymerization process, the crosslinking agent methylenebisacrylamide, the initiator ammonium persulfate and the catalyst are added Dithiocarbamates;

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

(3) adding mercaptoethylamine to the result of step (2) to carry out chemical grafting reaction to obtain the target product hydrogel copolymer.

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

Experimental example 1

A rat model of severe burn was constructed, and the hydrogel material obtained in Example 1 (taking the mass ratio of polyethylene glycol monomer to N-isopropylacrylamide monomer 1:3 as an example, the number average of polyethylene glycol Molecular weight is 3000) is used for the repair after burn, to explore the protective effect of the hydrogel material obtained in Example 1 on the recovery of local tissue in rats after burn and the inhibitory effect of systemic inflammatory response, and the methods are as follows:

40 rats were taken and divided into 4 groups, control group (Control), model group (Burn), positive control group (Burn+Intrasite Gel), experimental group (Burn+HydrogelA). All rats were shaved on the back, and 1 mL of 1% sodium pentobarbital was injected intraperitoneally for general anesthesia, and the area was taken as 30% of the total surface area (TBSA=K*W*0.5, K=0.9, W is the weight of the mouse): burn area. All rats except the control group were anesthetized and scalded in water at 99 degrees Celsius for 15 seconds, while rats in the control group were warmed in water at 37 degrees Celsius for 15 seconds after anesthesia.

Wounds were treated 1 day after burn. In the experimental group, the wounds were treated with the novel hydrogel dressing carrying CsA according to the present invention; in the positive control group, the wounds were treated with Intrasite Gel (a hydrogel dressing commonly used in clinical practice); the model group was not given any medication, and the other treatments were the same. . After the rats were anesthetized, the backs were cleaned and disinfected with chlorhexidine, and the drugs were administered according to the grouping conditions, with a thickness of 3-5 mm to prevent the drugs from falling off. At 3, 7, 10, and 14 days after burn, Image Pro Plus software was used to measure and record the wound healing process, calculate the scab surface area, wound healing rate, and complete healing time, and observe the morphological changes of the wound.

The statistical test results are shown in Table 1:

Table 1

Experimental example 2

The hydrogel prepared in "ACS applied materials & interfaces. 2017; 9(11): 9221-9225" was used in the above-mentioned severe burn model of rats, and recorded as positive control group 2. By loading CsA, it was similar to the experimental group of the present invention. The results are shown in Table 2:

Table 2

Experimental example 3

On the 3rd, 7th, 10th, and 14th days after the burn, blood was collected from the tail vein. The blood of 4 groups of rats was collected at each time point, and the serum was obtained by centrifugation. TNF-α levels.

The results obtained are shown in Tables 3 and 4:

table 3

Table 4

At the same time, 14 days after burn, the wound tissue was collected to detect the structural changes between the granulation tissues, the distribution of collagen and the expression of EFG-2.

The above experimental results show that the new hydrogel dressing carrying CsA can promote the healing of full-thickness burn wounds, improve the healing speed, reduce the release of inflammatory factors in the body, and promote the growth of endothelial cells.

Claims (8)

1. a triblock hydrogel copolymer with temperature response is characterized in that, described hydrogel copolymer is polymerized from polyethylene glycol monomer and N-isopropylacrylamide monomer An ABA type triblock network copolymer, the copolymer comprises a mussel biomimetic tissue adhesion group and a silver nanoparticle anchoring group, and the polyethylene glycol has a number average molecular weight of 3000-5000; the copolymer The molecular structure of the compound is shown in formula (I):

Wherein, the x, y, and z are all integers from 1 to n. 2 . The temperature-responsive triblock hydrogel copolymer according to claim 1 , wherein the mussel biomimetic tissue adhesion group is a dopamine group. 3 . 3 . The temperature-responsive triblock hydrogel copolymer according to claim 1 , wherein the nanoparticle anchoring group is a sulfhydryl group. 4 . 4 . The temperature-responsive triblock hydrogel copolymer according to claim 1 , wherein the mass ratio of the polyethylene glycol monomer to the N-isopropylacrylamide monomer is 1 to 4. 5 . 2:2-3. 5. The triblock hydrogel copolymer with temperature response according to claim 1 , wherein the hydrogel copolymer is in a liquid state at normal temperature or below body temperature, and is in a liquid state at body temperature or in contact with When the body surface changes to a gel state. 6. a preparation method of the triblock hydrogel copolymer with temperature response as described in any one of claims 1-5, is characterized in that, described preparation method comprises the following steps: (1) N-isopropylacrylamide monomer and polyethylene glycol monomer are firstly synthesized by RAFT polymerization method; (2) then replace the active ester group in the copolymer obtained in step (1) with the mussel biomimetic tissue adhesion group, and introduce the mussel biomimetic tissue adhesion group into the polymer; (3) adding mercaptoethylamine to the result of step (2) to carry out chemical grafting reaction to obtain the target product hydrogel copolymer. 7 . The preparation method according to claim 6 , wherein the synthesizing the copolymer in step (1) further comprises adding a cross-linking agent, an initiator and a catalyst. 8 . 8 . The preparation method according to claim 7 , wherein the crosslinking agent is methylenebisacrylamide, the initiator is ammonium persulfate, and the catalyst is dithiocarbamate. 9 .

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